Credit Note Guide: When and How to Issue One

A credit note is a document you send a customer to reduce or cancel an amount you've already invoiced them, and you issue one the moment you both agree the original bill was too high or is no longer owed. Goods came back. A job got cancelled halfway. You typed the wrong unit price. You promised a rebate after the invoice went out. In every one of those cases the fix is the same: leave the original invoice exactly where it is and issue a credit note against it. What follows covers when to issue one, what it has to contain, how the tax adjustment works in Singapore, and the errors that cause trouble later.

What Is a Credit Note?

Think of a credit note as a negative invoice. An invoice says "you owe me S$1,000." A credit note says "S$300 of that, you don't." It's issued by the seller, it references the invoice it's correcting, and it reduces the customer's balance without touching the original document.

That last part is the bit people get wrong. Your first instinct when you spot a mistake is to open the invoice and fix the number, or delete it entirely and start again. Don't. Invoice numbers have to run in an unbroken sequence, and a tax auditor comparing your ledger to your GST returns will notice a missing one. The credit note is what creates a clean paper trail: here's what I billed, here's what I took back, here's why. Both documents live in your records, and the net of the two is the real sale.

When Should You Issue a Credit Note?

The trigger is agreement. Once you and the customer accept that the invoiced amount is wrong or no longer stands, the credit note should follow quickly. The usual situations:

• Returned or faulty goods. The customer sends back part or all of an order because it's damaged, defective, or not what was described.
• Cancelled or reduced services. A retainer ends early, or a project gets scaled back after you've already billed for the full scope.
• Pricing and quantity errors. Wrong unit price, wrong hours, wrong quantity, wrong tax rate. Any overcharge on a sent invoice.
• Duplicate invoices. The same job billed twice. Credit the duplicate in full rather than quietly deleting it.
• Post-invoice discounts and rebates. A volume rebate, an early-settlement discount, or a goodwill reduction agreed after the bill went out.

On timing, the UK sets a hard deadline that's worth borrowing even if you're not trading there. HMRC's VAT Trader Records manual (VATREC13040) requires credit notes to be issued within 14 days of the decrease in consideration, under Regulation 15C of the VAT Regulations 1995. The same guidance sets out what makes a credit note valid at all: it must go to the customer, correct a genuine mistake or overcharge or reflect an agreed reduction in value, give real value to the customer, be issued in good faith, and not be used for a bad debt. That last exclusion catches people out. A customer who simply refuses to pay is a debt problem, not a credit note problem, and our guide to chasing late payments is the better starting point there.

Is a Credit Note the Same as a Refund?

No, and the difference is money moving. A credit note is the paperwork that reduces what's owed. A refund is cash actually going back to the customer. They often happen together, but they're separate steps and only one of them is always required.

If the invoice hasn't been paid yet, the credit note on its own does the job. It brings the balance down, and nothing leaves your bank account. If the customer has already paid, you issue the credit note and then decide with them what happens to the money: send it back, or leave the credit sitting on their account to offset their next invoice. Plenty of businesses prefer the second option because it keeps the cash and the relationship.

The practical rule: you can have a credit note without a refund, but you shouldn't have a refund without a credit note. The document is what justifies the tax adjustment.

What If You Undercharged Instead?

A credit note only moves in one direction. It reduces what the customer owes. So if you find you billed too little, reaching for a credit note is exactly backwards, and the document you actually need depends on whether GST was charged.

Here's where a lot of people get it wrong, because the obvious answer is "issue a debit note" and in Singapore that's often not right. IRAS guidance on invoicing customers is narrower than the popular usage: debit notes should be issued to request payment for transactions where no GST is charged, such as internal billings within the same company, or to suppliers from whom credit is due.

So for a standard-rated supply where you simply billed too little, the correct move is a new tax invoice for the shortfall, not a debit note. That new invoice carries the GST on the additional amount and drops into your output tax the normal way.

Sort it by situation:

• You billed too little on a GST supply. Issue an additional tax invoice covering the difference, referencing the original invoice number so the pair reads as one transaction.
• You need to correct a non-GST charge, or you're billing an entity within the same company. A debit note is the right document.
• The invoice is wrong in several directions at once. Credit the original in full and reissue it clean. Trying to patch a badly wrong invoice with a chain of adjustments makes the audit trail worse, not better.

One timing point worth knowing. IRAS treats the date any document serving as a bill for payment is issued, including a debit note, as triggering the time of supply for GST. So the document you send doesn't just record the extra charge, it sets which accounting period the tax falls into. Issue it in the wrong quarter and you've created a second problem to fix.

And a practical note on tone, because undercharging is awkward in a way overcharging isn't. Customers accept a credit note happily. An extra bill lands differently. Send it quickly, reference the original clearly, and state plainly what was missed. A correction that arrives four months later reads as either disorganised or opportunistic, and both cost you more than the amount usually justifies.

What Must a Credit Note Include?

A credit note is a formal document, so give it the same care as an invoice. At minimum:

• The words "Credit Note" clearly at the top, not "Invoice."
• A unique credit note number, from its own sequence such as CN-0001.
• The issue date.
• Your business name, address, and registration numbers. In Singapore that means your UEN and, if registered, your GST registration number.
• The customer's name and address.
• The original invoice number and its date, clearly referenced.
• The reason for the credit, in plain words. "Return of 5 units, damaged in transit" beats "adjustment."
• A description of the goods or services being credited, with quantities.
• The amount credited before tax, the tax amount being reversed, and the total.

The reason line matters more than it looks. It's the first thing a tax officer reads when they're deciding whether the adjustment was legitimate, and it's what stops an argument with the customer six months later. If you're unsure which registration details belong on your documents, our invoice checklist covers the same fields on the billing side.

How Do You Issue One, Step by Step?

The mechanics are simple once you've done it once.

1. Confirm the amount with the customer in writing. Email is fine. You want agreement on record before you credit anything.
2. Create the document. Start from the original invoice so the line items, tax rate, and customer details carry across, then change the title to "Credit Note" and give it a new number.
3. Credit only what's actually being reversed. A partial return means a partial credit note, not a full one.
4. Reference the original invoice number on the face of the document. Not in a covering email. On the credit note itself.
5. Send it and record it. Post it to your books in the period you issue it, and file it with the original invoice.
6. Settle the balance. Refund the money, or apply the credit against the customer's next invoice and note that you've done so.

One habit worth building: keep credit notes in their own numbering series, separate from invoices. It makes reconciliation faster and it stops a credit note ever being mistaken for a sale.

How Does GST Work on a Credit Note in Singapore?

This is the part that has real consequences. A credit note doesn't charge new tax. It reverses tax you already declared, which means it changes what you report on your GST return.

If you're GST-registered, the Inland Revenue Authority of Singapore (IRAS) expects the credit note to reference the original tax invoice, and the value of supplies you've credited feeds into the adjustment you declare in your GST return for the period. IRAS sets this out in its GST: General Guide for Businesses e-Tax Guide. Singapore's GST rate has been 9 percent since 1 January 2024, so a credit note reversing a 2024 or later sale reverses tax at 9 percent, not at whatever rate happens to apply when you issue it. Match the rate to the original invoice, always.

Then there's how long you hang on to it. IRAS requires GST-registered businesses to keep proper business and accounting records for at least 5 years, credit notes included, and that obligation survives you ceasing business or deregistering from GST. Records can be physical or electronic. Fail to keep them and IRAS can disallow input tax claims or impose penalties, which is a costly outcome for a document you could have saved as a PDF. For the wider set of GST rules on the invoicing side, see our GST invoice guide.

Can You Issue a Credit Note Without Touching the GST?

Yes, and IRAS allows it explicitly. This is the part of the credit note rules that most small businesses have never heard of, and it can save you a genuinely annoying amount of admin when the adjustment is commercial rather than tax-related.

Here's the situation it solves. You've invoiced a client, GST was charged correctly, and now you want to knock something off. A goodwill discount for a delay that was your fault, say, or a negotiated reduction on a long project. The supply itself hasn't changed. Nothing was wrong with the original tax treatment. But a standard credit note drags both of you into adjusting your GST returns anyway, and if you're on different filing cycles that's two sets of corrections for something neither of you thinks of as a tax event.

The concession on IRAS's invoicing guidance lets you skip that. If you and your customer agree in writing not to adjust the original GST amount, you can issue the credit note without changing the tax, and the document must carry the statement "This is not a credit note for GST purposes". Do that, and neither side adjusts the value of their taxable supplies or purchases, and neither side touches output or input tax.

Two details make this more usable than it first sounds.

The written agreement doesn't have to be a contract. Correspondence between the two of you is enough, and that includes ordinary email. So a reply from your client saying they're happy to take the reduction without a GST adjustment, kept in your records, does the job. You don't need anyone's signature or a lawyer.

And the statement wording matters. It's a specific line that tells any future auditor, on both sides, exactly why this document didn't move through the GST returns. Leave it off and you've just issued an ordinary credit note that should have been adjusted, which is a harder conversation later.

When to actually use it:

• Goodwill and commercial gestures. A discount you're offering to keep a client happy, where the original supply and its GST were both correct.
• Small adjustments across different filing cycles. If the amount is minor and you file quarterly while they file monthly, the coordination cost can exceed the sum involved.
• Late renegotiations on work already delivered and correctly taxed.

And when not to:

• The original invoice was actually wrong. Wrong amount, wrong rate, wrong GST treatment. That's an error, it needs a real adjustment, and this concession isn't a shortcut around fixing it.
• Goods came back or the supply was cancelled. The taxable supply genuinely changed, so the GST genuinely changes with it.
• Your customer isn't GST-registered or won't agree. It takes both of you. No written agreement, no concession.
• You want the output tax back. Worth stating plainly, because it's the catch. Skipping the adjustment means you don't reclaim the GST you already accounted for on the reduced portion. You're trading that money for the admin. On a small goodwill discount that's usually fine. On a large one, do the sum first.

That last point is the whole decision, really. The concession buys simplicity and costs you the tax adjustment. Work out which is bigger before you reach for it, and if the amount is meaningful or your situation doesn't sit cleanly in the examples above, put it to your accountant or check directly with IRAS rather than reading this paragraph as permission.

Which Boxes Does a Credit Note Change on Your GST Return?

Here's where a lot of guidance online gets it wrong, so it's worth being precise. A credit note is not an error correction. It's a normal adjustment, and it goes in your ordinary quarterly return.

IRAS gives a worked example on its Correcting Errors Made in GST Return (Filing GST F7) page. If you made a sale on 1 January and issued a credit note against it on 30 June, and GST was correctly accounted for at the time, you reduce your value of standard-rated supplies in Box 1 and your output tax due in Box 6 in the GST F5 for the accounting period covering June. That's the period the credit note was issued, not the period of the original sale. And IRAS states plainly that you should not file a GST F7 for credit note adjustments.

The F7 is for something else: genuine mistakes in returns you've already filed. If you do have those, IRAS offers an administrative concession letting you fix them in your next F5 instead, but only when both conditions are met. The net GST amount in error across all affected periods must be no more than S$3,000, and the total amount in error for all boxes other than Boxes 6, 7 and 12 must be no more than 5 percent of the total value of supplies in Box 4 for each affected period. Miss either threshold and you file the F7, which supersedes the earlier return entirely.

There's an edge case in that second test worth knowing if you have quiet quarters, because 5 percent of nothing is nothing. Where you made no supplies at all in an affected period, IRAS applies the 5 percent rule to the total value of your taxable purchases in Box 5 instead of to Box 4. So a dormant quarter doesn't automatically push you into filing an F7. It just changes which number the percentage is measured against.

Two deadlines to keep in view. Errors have to be corrected within five years from the end of the relevant GST accounting period, and IRAS may impose penalties on corrections made more than one year after that period ends. So finding a problem early is worth real money.

What If the Invoice Was From a Financial Year You've Already Closed?

You can still issue the credit note. What changes is how many people need to know about it, and that depends entirely on how far through your year-end process you've got.

The GST side is already settled by the rule above. The credit note lands in the accounting period you issue it, not the period of the original sale, so your GST returns take care of themselves. The complication is on the accounts side, and it has three stages.

Stage one: the year has ended but nothing is filed. This is the easy case and it's where most small businesses are for several months. Your bookkeeping year is closed, but the numbers haven't gone anywhere official yet. Talk to whoever prepares your accounts before you issue. A credit note that relates to a sale in the closed year may need to be reflected in that year rather than the current one, because it tells you something about what that sale was really worth.

Stage two: the accounts are prepared but not yet approved. Now timing matters. In Singapore, a private company must hold its AGM within six months of its financial year end, and file its annual return with ACRA within seven months. Public companies get five months for the return. The controlling deadline is whichever comes first: one month after the AGM, or the seven month mark. That gives you a real window, and a credit note raised inside it is far cheaper to deal with than one raised after.

Stage three: the annual return is filed. Once the numbers are lodged, changing them is a formal exercise rather than a bookkeeping one. For most small businesses the practical answer is that the credit note goes through the current year, and nobody restates anything. That's normal and it's fine. Restating a filed set of accounts is reserved for errors that are genuinely material, and one credit note usually isn't.

Whether an auditor is involved changes the temperature of all of this. A Singapore company can claim small company audit exemption if it meets at least two of three tests: revenue of S$10 million or less, total assets of S$10 million or less, and 50 employees or fewer. If you're under those thresholds and unaudited, stage three is genuinely just a conversation with your accountant. If you're audited, raise it with them early rather than at the next year end.

Two practical habits make all of this easier:

• Do a credit note sweep before you close. Before the books shut, check for disputed invoices, agreed discounts nobody documented, and returns that were accepted verbally. Issuing those inside the year costs nothing. Issuing them afterwards costs a conversation.
• Never leave a known credit sitting to avoid the paperwork. An invoice both sides know will not be paid in full is not a receivable. Carrying it makes your year end look better than reality, which is the opposite of what accounts are for.

And do not let the deadline pressure push you into filing late. ACRA penalties for late annual return filing run up to $600, which is considerably more than the credit note is likely to be worth. If you're a sole proprietor rather than a company, none of the ACRA timeline applies to you, though the tax year cut-off still does. Our Singapore freelancer tax guide covers how that works.

Is There a Deadline for Issuing a Credit Note?

Yes, and it catches people out because there are two separate clocks running and most guides only mention one. There's a rule about how quickly you must issue once something changes, and a rule about how far back you're allowed to reach. They're different, they're set by different bits of the rulebook, and in at least one jurisdiction they interact in a way that rewards doing it properly.

Start with the distinction, because it's the useful part.

Clock one is promptness. Once you and the customer agree the amount owed has gone down, a countdown starts. Not from the original invoice date. From the moment the change happens.

Clock two is reach. How old an invoice can you still adjust at all. This is the one people actually want answered, usually while looking at something from two years ago.

The clearest published version of both comes from HMRC, which is worth reading even if you don't invoice into the UK, because it's the rule set most explicitly written down.

On promptness, HMRC's guidance on what makes a credit note valid requires it to be issued within 14 days of the decrease in consideration. Fourteen days from the agreement or the refund, not from the invoice. That's a genuinely short window and it's the one most small businesses blow through without realising there was one.

On reach, the answer is more interesting than a flat number. HMRC's guidance on whether the four-year capping provisions apply says adjustments properly made under Regulation 38 may relate to tax periods older than four years. But it also says that failing to make a genuine adjustment in the right period is an error, and errors must be corrected within four years of that period.

Read those two sentences together, because the logic is worth internalising even outside the UK.

Do it properly and there's effectively no age limit on the underlying adjustment. Do it late and you've converted a routine adjustment into an error, and errors come with a four-year ceiling. The deadline isn't punishing you for the age of the invoice. It's punishing you for the delay in handling it.

That principle travels. Most tax authorities are relaxed about correcting genuine changes and much less relaxed about businesses sitting on known adjustments until it suits them.

How this looks elsewhere.

• Singapore. There's no published 14-day equivalent. What bounds you in practice is the five-year record-keeping requirement and the correction route for returns you've already filed, both covered in the section on invoices from a closed financial year above. If you can't produce the original tax invoice, you have a bigger problem than the credit note.
• Malaysia. Guidance points at issuing within the taxable period in which the adjustment is identified, or promptly afterwards. The expectation is the same shape as the UK's: deal with it when you find it.
• The EU. Correction rules sit with individual member states rather than being harmonised into one number, so if you invoice into several, check each. The Commission's invoicing rules linked earlier in this guide are the starting point.
• Everywhere else. If your jurisdiction publishes nothing specific, the defensible position is to issue in the same reporting period you agreed the change. That satisfies almost every rule that exists and it's what an auditor will expect to see.

The practical rules that hold regardless of where you are:

• Date it when you agreed, not when you remembered. The date on the credit note should reflect when the adjustment was actually agreed. If a month has passed, use today's date and note the agreement date in the body. Do not quietly backdate it into a closed period, which is a different category of problem entirely.
• The trigger is the event, not the invoice. Goods returned, discount agreed, service cancelled, error accepted. That's your start date. An invoice from three years ago that a customer returned goods against last week is a fresh adjustment, not an old one.
• Log the agreement date in the credit note. One line saying the return was accepted on a particular date turns a late credit note into a documented one. That distinction matters if anyone ever asks.
• Sweep before each reporting period closes, not just at year end. If you file quarterly, run the check quarterly. The whole point of clock one is that adjustments are meant to land in the period they arise.
• Age is a reason to check, not a reason to skip. People talk themselves out of issuing an old credit note because it feels awkward. Carrying a receivable you know will never be collected is worse, and the section on invoices that will never be paid covers the route for that case specifically.

One last thing worth separating out. Everything above is about the tax adjustment. The commercial document has no deadline at all. If a customer is owed a correction, you owe them a correction, and no rule about reporting periods changes that. The two questions are answered by different people, and it's the tax one that has a clock on it.

What Do You Do When You Receive a Credit Note?

Everything so far has been written from the seller's chair. But you'll be on the receiving end at least as often, and the obligation that lands on you is the mirror image: you have to reduce the input tax you already claimed on that purchase.

That's the bit worth sitting with, because the risk here sits with you and not your supplier. If a credit note arrives and you file it without touching your books, you have claimed input tax on money you never actually spent. Your supplier has already reduced their output tax at their end. Yours no longer matches, and it's your return that's overstated.

So check it before you accept it. Wrong credit notes are commoner than you'd think, usually because someone credited the wrong invoice from a customer with several open:

• Does it reference an invoice you actually hold? Match the number and the date, not just the supplier name.
• Is the amount what you agreed? A partial return should produce a partial credit. If the figure is rounder than the conversation was, query it.
• Is the GST reversed at the original invoice's rate? The same rule that applies to issuing applies to receiving. A 2023 invoice reverses at the old rate, not at 9 percent.
• Is it actually a credit note? A supplier emailing "ignore the last invoice, we'll sort it" is not a document. You need the paperwork before you can adjust anything.

Then record it in the period you receive and accept it, the same way the seller records it in the period they issue it. Keep it with the original purchase invoice for the same 5 years IRAS requires of everything else, because the pair is what justifies your adjusted input tax claim if anyone asks.

One wrinkle worth flagging if you buy in foreign currency, because this guide can't settle it for you. Which exchange rate applies to a credit note against a US dollar invoice is a genuine question with a genuine answer, and it isn't automatically the rate on the original invoice. IRAS covers the treatment on its Foreign Currency Transactions page, and if a meaningful share of your purchases are billed in another currency it's worth reading before you set a house rule, since applying the wrong one consistently compounds quietly across a year.

And if you're on InvoiceNow, receiving stops being a filing task and becomes a transmission one. The next section covers what that involves.

What Changes Under Singapore's InvoiceNow Rules?

Everything above still holds. But if you're GST-registered in Singapore, a credit note is turning into something you send to IRAS as well as to your customer, and the date that starts applying to you depends on your turnover.

IRAS set the rules out in its e-Tax Guide Adopting GST InvoiceNow Requirement for GST-Registered Businesses, second edition published 9 March 2026. Invoice data gets transmitted to IRAS through the InvoiceNow network via IMDA-accredited Access Point providers. Here's the phase-in:

• 1 Nov 2025. Newly incorporated companies registering for GST voluntarily, meaning companies incorporated within 6 months of applying.
• 1 Apr 2026. All new voluntary GST registrants, whatever their incorporation date or business structure.
• 1 Apr 2028. All new compulsory registrants, plus existing businesses with total annual supplies of $200,000 or less.
• 1 Apr 2029. Existing businesses with total annual supplies of $1,000,000 or less.
• 1 Apr 2030. Existing businesses with total annual supplies of $4,000,000 or less.
• 1 Apr 2031. Existing businesses with total annual supplies above $4,000,000.

Your phase is fixed by your total annual supplies across all prescribed accounting periods ending in calendar year 2025. That's Box 4 on your F5, the total of standard-rated, zero-rated and exempt supplies. So the number that decides your deadline is already sitting in returns you've filed.

You don't have to work it out alone, either. IRAS says it will write to businesses that were GST-registered before 2026 to tell them their mandatory implementation date, and it publishes a self-help calculator so you can check where you land before that letter arrives. There's money attached to moving early too: transitional funding to offset onboarding costs, and InvoiceNow-Ready Solutions free to SMEs until March 2031. If you're going to end up on the network anyway, doing it while someone else is paying for it is the cheaper order to do things in.

Worth knowing what "transitional funding" actually means in money, because most write-ups leave it vague. IMDA runs two GST InvoiceNow Transition Grants: one worth up to $1,000 for businesses with total annual supplies of $4 million or less, and one worth up to $5,000 for businesses above that line. Same turnover figure that sets your phase, so if you've worked out your deadline you already know which grant applies to you. You claim it after you've actually activated InvoiceNow and started sending invoice data to IRAS, and you need to have done that before your own compliance deadline.

Check the current claim window on IMDA's page before you plan around it. The two grants don't close on the same date, and published summaries disagree about when the smaller one ends, so go to the source rather than trusting a secondhand figure. That includes this one.

Now the part specific to credit notes, and it's more demanding than most summaries let on. IRAS counts credit notes and debit notes as invoice data, alongside sales invoices, tax invoices, simplified tax invoices and serially numbered receipts. Sales orders, statements of account and pro-forma invoices are explicitly not invoice data, which is a useful line to know and one reason a pro-forma invoice sits in a different category from the real thing.

Four rules are worth having in front of you, and IRAS flags several of them as carrying the force of law:

• Credit note data must be sent to IRAS. Not optional, and it applies whether or not the credit note adjusts GST. If you and your customer agree not to adjust the GST amount, you still transmit the credit note and still apply GST category code "SR".
• Cancelling an invoice means issuing a credit note. IRAS says so directly, which settles the argument in favour of what this guide has been telling you all along. The amounts and GST category codes have to tally with the original invoice's mandatory data elements.
• The original invoice number and date go in specific fields. Preceding Invoice Number (IBT-025) and Preceding Invoice Date (IBT-026). If you genuinely can't identify the original invoice you may leave them blank, but you then have to keep documentary evidence that GST was accounted for on the original supply.
• Credit notes you receive count too. If a supplier credits you, you receive it, validate it, accept it in your system, and submit that data to IRAS with the reduced taxable purchase amount and input tax. Alternatively you can submit revised purchase data net of the adjustment.

One more detail that catches people out on mixed invoices. If even a single line item on a credit note falls within the requirement, the entire credit note has to be transmitted, not just the in-scope lines.

What this means practically is that the habits in this guide stop being good practice and start being compliance. Referencing the original invoice number was always sensible. Under InvoiceNow it's a named data field. Keeping credit notes in a clean sequence and matching them to their invoices was always tidier. Now it's what stops a validation failure. If you're on the network already, or your phase is coming, getting this right on paper first makes the transition considerably less painful.

Does Malaysia Handle Credit Notes Differently?

Yes, and if you bill across the causeway it's worth knowing. Under Malaysia's e-Invoice framework, the Inland Revenue Board of Malaysia (IRBM/LHDN) e-Invoice Guideline, version 4.7 published 7 July 2026, splits what Singapore treats as one document into several. There are five document types in the system: the invoice, the credit note, the debit note, the refund note, and self-billed versions of these.

The split that matters here is between the credit note and the refund note. LHDN's own developer documentation defines a credit note as the document a supplier issues to correct errors, apply discounts or account for returns on a previously issued e-Invoice, reducing its value, and says plainly that it's used where the reduction does not involve return of monies to the buyer. When cash actually goes back, that's a refund note. So the Singapore habit of using one credit note to cover both the adjustment and the money moving doesn't map cleanly onto MyInvois.

There's a second difference that matters more day to day, and it's about timing. In Singapore you can issue a credit note against an invoice from years ago. Malaysia puts a hard clock on the alternative route.

Once an e-Invoice is validated, the supplier has 72 hours to cancel it, and the buyer has the same 72 hours to request a rejection through the MyInvois Portal. Miss that window and cancellation stops being available at all. The only way to adjust the document after that is to issue a new e-Invoice: a credit note, a debit note or a refund note. LHDN sets this out in its e-Invoice Guideline, now at version 4.7.

That flips the mental model. In Singapore a credit note is what you reach for when something needs correcting. In Malaysia it's also what you're forced into once three days have passed, which means credit notes are a routine part of the workflow rather than an exception. Plan for volume.

Three practical details from LHDN's MyInvois SDK documentation that catch people out:

• The original document is referenced by UUID, not invoice number. You put the affected e-Invoice's Unique Identifier Number in the Original e-Invoice Reference Number field. That's the validated system identifier, not the invoice number you printed on it.
• Old invoices use "NA". If you're adjusting an invoice issued before e-Invoice applied to you, there's no UUID to reference. LHDN allows you to enter "NA" in that field rather than blocking the adjustment.
• One credit note can cover several invoices. To reference a second original e-Invoice you add another line at Billing Reference in XML, or at InvoiceDocumentReference in JSON. Useful when one negotiated settlement wipes out part of three invoices at once.

One caution on the timeline. Malaysia's e-Invoice rollout has been phased by annual turnover and the thresholds have been revised more than once, including a change to the exemption floor and an extended relaxation period. The guideline itself has moved through several versions. So check your own phase against the current guideline rather than against a summary written a year ago, this one included.

Note too that Malaysia runs SST rather than GST, so the tax treatment differs as well as the paperwork. Our Malaysia SST invoice guide and Singapore vs Malaysia invoicing comparison cover the rest of the differences.

What Are the Rules If You Invoice Into the EU?

Broadly similar in shape, with one requirement stated more explicitly than most tax authorities bother to state it.

The European Union runs what the European Commission describes as a single set of basic EU-wide VAT invoicing rules, sitting alongside national rules that each member state sets for itself. So there's a common floor across all 27 countries, and then local variation on top. That matters if you're selling into more than one of them, because the floor is the part you can rely on everywhere.

On credit notes specifically, the EU rule is refreshingly concrete. Under the invoicing rules set out in Council Directive 2010/45/EU, a credit note, debit note, or any other document amending an earlier invoice has to carry a specific and unambiguous reference to the initial invoice and to the details being amended.

Read that carefully, because it's two obligations rather than one.

Referencing the original invoice number is the obvious half, and most people do it. The second half catches people out. You also have to be specific about what you're changing. A credit note that references invoice INV-1042 and then just shows a total is doing half the job. One that references INV-1042 and shows the two line items being reversed, with the amounts and the VAT on each, is doing all of it.

That's the same discipline the earlier sections of this guide recommend anyway, so if you've been following those you're already compliant. But in the EU it isn't a best practice. It's the rule.

Three other things worth knowing

Electronic credit notes are equivalent to paper ones. The Commission is explicit that electronic invoices carry the same standing, provided the recipient accepts them. Business-to-government transactions are the exception, where structured electronic invoices must be accepted. So a PDF credit note emailed to a customer is a real credit note, not a placeholder for one.

You can outsource issuing, including to your customer. Self-billing arrangements are permitted, where the buyer raises the document on your behalf. Useful in some supply relationships, and worth knowing exists rather than discovering it in a contract.

Storage is flexible, but the details are national. Businesses have wide latitude on where and in what format they keep invoices and credit notes. How long you must keep them, though, is set by individual member states rather than at EU level, so that's one to check against the specific country rather than assume.

And that last point generalises. The EU harmonises the baseline and leaves plenty to national law, so if you're invoicing into a specific member state regularly, the local rules are worth twenty minutes of your time. The Commission maintains a database of country-specific provisions for exactly this.

If you are issuing across several currencies as well as several jurisdictions, be aware that exchange rate treatment is another area the EU leaves largely to national rules. The section further up this guide on foreign currency explains why that particular question needs answering against a specific tax authority rather than a general principle, and the same caution applies across member states.

Do Credit Notes Affect How Fast You Get Paid?

More than most people expect. A disputed invoice usually sits unpaid in full, not partly paid, and the customer's accounts team will often park the entire thing until the paperwork matches what they think they owe. Issuing the credit note is what unfreezes it.

The scale of the problem is measurable. Atradius, in its Payment Practices Barometer for Singapore published on 23 July 2025, found that an average of 35 percent of all B2B sales transacted on credit are affected by overdue invoices, and it names invoice disputes alongside customer liquidity as the two main drivers of those late payments. Across Asia the same survey, run in the second half of Q2 2025, put the regional overdue figure at 44 percent of B2B credit sales, with bad debts averaging around 5 percent of invoices. Read those numbers together and the message is blunt. A meaningful slice of the money you're waiting on isn't stuck because the customer can't pay. It's stuck because the document is wrong and nobody has corrected it.

That's the argument for issuing credit notes fast rather than batching them up at month end. Every week a disputed invoice sits uncorrected is a week the clock doesn't start on the corrected amount. The customer isn't refusing to pay you. They're waiting for a number they can approve. Send the credit note, restate the balance, and the invoice moves back into their normal payment run instead of their exceptions pile.

There's a second benefit that shows up later. Clean credit notes make your accounts receivable ageing report trustworthy. If overdue balances on your books include amounts you already know you'll never collect because the work was cancelled, you're chasing ghosts and your cash forecast is wrong. Credit them off properly and what's left is real money you can actually go after. Our guide to chasing late payments works far better when the ledger underneath it is accurate.

What Should You Do About an Invoice That Will Never Be Paid?

This guide has told you twice now that a credit note is the wrong tool for a customer who simply won't pay. Fair enough. But that leaves an obvious question hanging, because you've paid GST to IRAS on money you never received. The route back is bad debt relief, and it's a genuinely different process with its own conditions.

The distinction is worth stating plainly. A credit note says the customer never owed that amount. Bad debt relief says they owed it and didn't pay. Same hole in your bank account, completely different paperwork, and only one of them is honest about what happened.

IRAS sets conditions you have to meet before claiming, and they all have to hold:

• You supplied goods or services for a consideration in money, and you accounted for and paid GST on that supply.
• You've written off the whole or part of the consideration as a bad debt in your accounts. Deciding privately that you'll never see the money isn't enough. It has to be in the books.
• Twelve months have passed since the date of supply, or the debtor became insolvent before those twelve months elapsed.
• You've taken reasonable steps to recover the debt.
• The value of the supply is equal to or below its open market value.
• For goods, ownership has transferred to the customer.

Two of those trip people up. The twelve month wait means this is never a quick fix, so it's not an alternative to chasing the invoice properly. And "reasonable steps to recover" means your paper trail matters: the reminders, the statements, the letters. If you wrote the debt off without ever seriously pursuing it, you've failed a condition. Our guide to chasing late payments is where that trail gets built, and it's doing double duty here.

IRAS asks you to complete its Bad Debt Relief self-review checklist first, then claim the relief in Box 7 of your GST return, the input tax and refunds claimed box. Keep the completed checklist with your records rather than sending it in.

One rule that catches people later: if the customer eventually pays, you have to repay the relief you claimed. A written-off debt that turns into a surprise payment eighteen months on is a good day for cash flow and a thing you must remember to reverse.

The practical sequence, then. Chase properly and keep the evidence. If it becomes clear the money isn't coming, write it off in your accounts. Wait out the twelve months unless the customer has gone insolvent. Run the checklist, claim in Box 7, and keep the paperwork. What you don't do is quietly issue a credit note to make the receivable disappear, because that misstates what happened and, as covered above, the UK guidance rules it out explicitly for the same reason.

What Mistakes Should You Avoid?

Five errors account for most of the trouble, and all of them are avoidable.

• Editing or deleting the original invoice. It breaks your number sequence and looks like you're hiding something. Issue the credit note instead.
• Leaving off the original invoice number. Without it, nobody can match the two documents, and the adjustment is hard to defend.
• Using the wrong tax rate. The credit note follows the rate on the original invoice, not today's rate.
• Writing "adjustment" as the reason. Vague reasons invite questions. Say what actually happened.
• Using a credit note to write off a bad debt. HMRC explicitly rules this out, and it's poor practice generally. Unpaid is not the same as not owed.

The thread running through all five is the same: a credit note is a correction, not an eraser. Its whole value is that it shows the original figure, the change, and the reason side by side. Our common invoice mistakes guide covers the errors that lead to needing one in the first place.

What Else Do People Ask?

What is a credit note used for?

A credit note is used to reduce or cancel an amount a customer owes you on an invoice you've already issued. It's the correct fix for returned goods, cancelled work, overcharges, pricing errors, and after-the-fact discounts. You never delete or edit the original invoice. You leave it in place and issue a credit note against it.

When should you issue a credit note?

Issue one as soon as you and the customer agree the invoiced amount was too high or is no longer owed. Common triggers are returned or faulty goods, cancelled services, wrong quantities or unit prices, duplicate invoices, and volume rebates agreed after billing. HMRC requires credit notes within 14 days of the decrease in consideration, which is a sensible deadline to work to anywhere.

Is a credit note the same as a refund?

No. A credit note is the accounting document that reduces what's owed. A refund is money physically going back to the customer. If the invoice is unpaid, a credit note alone settles it. If they've already paid, you issue the credit note and then either refund the cash or leave the credit on account for their next invoice.

Can you cancel an invoice with a credit note?

Yes, and that's the proper way to do it. To cancel an invoice in full, issue a credit note for the entire value including tax, referencing the original invoice number. Don't delete the invoice or change its numbering. Your invoice sequence has to stay unbroken, and a tax auditor will want to see both documents.

How long must you keep credit notes?

In Singapore, IRAS requires GST-registered businesses to keep proper business and accounting records, credit notes included, for at least 5 years, and that still applies if you've ceased trading or deregistered from GST. Failing to keep them can mean input tax claims are disallowed or penalties are imposed. Electronic copies are acceptable.

Sources: Inland Revenue Authority of Singapore (IRAS) on invoicing customers, keeping records, correcting errors made in GST returns (filing GST F7), the GST: General Guide for Businesses e-Tax Guide, and the e-Tax Guide "Adopting GST InvoiceNow Requirement for GST-Registered Businesses" (Second Edition, published 9 March 2026) on phased adoption and credit note transmission; HMRC VAT Trader Records manual VATREC13040 on valid credit notes and the 14-day rule under Regulation 15C, VAT Regulations 1995; Inland Revenue Board of Malaysia (IRBM/LHDN) e-Invoice Guideline on credit notes and refund notes; Infocomm Media Development Authority (IMDA) on the GST InvoiceNow Transition Grants; Atradius Payment Practices Barometer, Singapore 2025 (published 23 July 2025) on overdue B2B invoices and invoice disputes. All linked above.

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