GST GUIDE · UPDATED SEPTEMBER 2026
Late for GST registration: the penalties can be waived, the backdated tax cannot
A company’s taxable turnover passes S$1 million in December 2025. Nobody checks on 31 December, and the 2025 accounts are not finished until September. By then IRAS will date the company’s GST registration from 1 March 2026, the day it should have started, and the company owes GST on every sale since, at prices that never included it. Coming forward gets the fine and the penalty waived. It does not get the tax waived. This guide covers how the bill is worked out, how much of it can be recovered from customers, and what to do, in order, if you are already late.
THE BILL
Seven months late: S$57,798, or S$17,339.
Take an events production company: nine staff, corporate clients and private ones. Its taxable turnover was S$870,000 in 2024 and S$1,084,000 in 2025; it passed S$1 million in the first week of December. The test date was 31 December 2025, the application was due by 30 January 2026, and registration would have started on 1 March. The owner finds out on 30 September, when the 2025 accounts are being finalised for the tax return. Between 1 March and 30 September the company invoiced S$700,000 with no GST: S$490,000 to GST-registered companies and S$210,000 to individuals and organisations that are not registered.
| 1 March to 30 September 2026, S$ | Nothing recovered | Registered customers pay |
|---|---|---|
| Output tax on S$490,000 billed to GST-registered companies | 40,459 | 44,100 |
| Output tax on S$210,000 billed to private customers | 17,339 | 17,339 |
| Output tax for the seven months | 57,798 | 61,439 |
| Input tax on purchases since 1 March | −16,200 | −16,200 |
| GST on equipment bought in January and still held | −3,600 | −3,600 |
| Payable to IRAS | 37,998 | 41,639 |
| Collected from customers | 0 | 44,100 |
| Output tax the company funds itself | 57,798 | 17,339 |
The two columns differ in one line. Where a customer cannot or will not be asked to pay, what they have already paid is treated as the whole price, GST included, and the tax is 9/109 of it: 8.26%, not 9%. Where a customer agrees to pay, the GST is 9% on top and the customer funds it. GST-registered customers usually agree, because they claim it back on their own return; it costs them a quarter’s wait and some paperwork. Private customers have no reason to.
The two claims against the output tax are the same in both columns. In the seven months the company bought S$180,000 of goods and services from GST-registered suppliers and paid S$16,200 of GST on them. It also bought S$40,000 of lighting equipment in January, inside the six months before its registration date and still held on it, which carries another S$3,600. Neither is a consolation for being late. The company would have claimed both if it had registered on time. What lateness costs is the output tax nobody else funds: S$57,798 if no customer is asked, S$17,339 if every registered customer pays.
Measure it against profit, not sales.
If the company keeps 10% of its sales as profit, those seven months earned S$70,000. Absorbing S$57,798 takes more than four-fifths of it. Had someone run the test on 31 December, the company would have applied in January and had until 1 March to reprice, requote and tell its customers. The S$63,000 of GST on the same seven months would have been added to its invoices and paid by the people it invoiced.
WHAT IRAS WAIVES
The tax is fixed. The punishment depends on who speaks first.
| Consequence | If IRAS finds you | If you come forward first |
|---|---|---|
| Registration date | Backdated to the day you should have been registered. | The same. IRAS says this cannot be waived. |
| GST on sales since that date | Payable in full, whether or not you collected it from customers. | The same. If paying at once is difficult, IRAS may allow instalments. |
| Fine for late notification | Up to S$10,000. Prosecution may apply. | Generally waived. |
| Penalty | 10% of the GST due. | Generally waived. |
“First” has a precise meaning. A disclosure is voluntary only if it is made before IRAS sends a query or a notice of audit, is accurate and complete, and is followed by payment or a payment arrangement that is kept. For a late registrant, the disclosure is made in the registration application itself, on myTax Portal.
Two cases IRAS has published.
A services business that did not monitor its taxable supplies was found on audit to be five years late. It absorbed S$1,150,000 of GST it could not fully recover from customers, and paid S$55,000 in penalties. A construction business, found four years late after several educational letters from IRAS, paid S$405,000 of backdated GST and S$3,000 in penalties. In both, the penalty was the small number.
THE TWO TESTS
One test on 31 December. The other on the day you sign.
Registration is compulsory when either test is failed. Each has its own date, its own deadline and its own starting day, and a late registration is backdated to whichever starting day came first.
| Aspect | Retrospective view | Prospective view |
|---|---|---|
| The question | Did taxable turnover for the calendar year, 1 January to 31 December, exceed S$1 million? | Can you reasonably expect taxable turnover to exceed S$1 million in the next 12 months? |
| When it is asked | On 31 December, every year. | On any day. In practice, the day a contract is signed, a quotation is accepted or a tender is won. |
| What settles it | The books: taxable sales for the twelve months. | Evidence of certainty: signed contracts, accepted quotations, confirmed purchase orders, fixed monthly fees, or accounts showing the last 12 months close to S$1 million and rising. A business plan or a sales target is not enough to create the liability. |
| Apply | Between 1 and 30 January. | Within 30 days after the date of the forecast. |
| Registered from | 1 March. | Two months after the date of the forecast, for liabilities arising on or after 1 July 2025. Before that, it was the 31st day. |
| In dates | Turnover for 2026 above S$1 million: apply by 30 January 2027, registered from 1 March 2027. | IRAS's example: a quotation accepted on 2 September 2025 means applying by 2 October and registration from 2 November 2025. |
Passing S$1 million in September does not, by itself, require anything in September. If nothing makes the next twelve months certain to exceed S$1 million, IRAS’s position is that you wait for 31 December and test then. If a signed contract does make it certain, the prospective test has already started its 30 days.
Two ways out, both with paperwork.
A business whose taxable supplies are more than 90% zero-rated, and which would be in a net refund position if registered, can apply for exemption on form GST F2. It is an application, not an assumption. And a business that passed S$1 million for the calendar year need not register if it is certain the next twelve months will not, because of a specific event: a major contract ending, a large-scale downsizing, a licence or distribution right lost, or the business closing. IRAS lists those four circumstances and expects documents and a computation for whichever one applies. A good year that may not repeat is not on the list. Either way, the test comes round again the following 31 December.
HOW IT GOES UNNOTICED
Five ways a business passes S$1 million without seeing it.
The test runs on the calendar year. Your accounts may not.
A company with a 30 June year-end reports S$900,000 for the year to June 2025 and S$980,000 for the year to June 2026. Neither set of accounts shows S$1 million. But January to June 2025 was S$520,000 and July to December was S$510,000: S$1,030,000 for the calendar year, and a registration date of 1 March 2026 that no report the owner reads would ever reveal.
The accounts arrive after the window has closed
A December year-end company sees its annual accounts in the middle of the following year, often later. The application window closed on 30 January. The test does not need finished accounts. It needs one number, taxable sales for the twelve months, and the books can give it in the first week of January.
Exports count
Zero-rated sales are taxable turnover. A business selling S$700,000 in Singapore and S$400,000 overseas has S$1.1 million of taxable turnover, even though the exports carry GST at 0%. What stays out is narrower than most owners assume: exempt supplies, out-of-scope supplies such as goods shipped from one overseas country to another, and the sale of capital assets.
A signed contract is a forecast
The prospective test does not wait for revenue. In IRAS's own example, a tender secured on 31 December 2025, for work to be invoiced over the following year, meant applying by 30 January 2026 and being registered from 28 February. The 30 days run from the signature, which is usually a day when nobody in the business is thinking about GST.
A sole proprietor is one person, however many businesses
A sole proprietor adds together every sole-proprietorship business they own, registered with ACRA or not, and any income from a trade, profession or vocation. Two businesses at S$600,000 each are S$1.2 million. Partnerships with the same partners are combined in the same way. A company is tested on its own.
IF YOU ARE ALREADY LATE
Six steps, in this order.
Find the date you should have been registered
Test every 31 December that could have failed, using taxable turnover for that calendar year. Then test the dates of large contracts, accepted quotations and tenders. The earliest failure sets the date: 1 March after the calendar year, or, for a forecast made on or after 1 July 2025, two months after it. Everything else in this list is measured from that date.
Apply now, and say that you are late
Apply on myTax Portal and disclose the lateness in the application, before IRAS writes to you. A disclosure made after a query or a notice of audit is no longer voluntary, and the waiver of the fine and the penalty depends on it being voluntary, accurate and complete. IRAS processes 60% of applications within 10 working days and the rest within 30 days.
Do not charge GST until the approval letter arrives
Submitting the application does not make you registered. IRAS's instruction is to start charging only once the approval letter gives you a registration number and an effective date; until then you cannot issue a tax invoice. Use the wait. Tell customers that GST is coming, and quote all new work as subject to GST.
Go back to customers for the GST on past invoices
They owe it only if they agree to pay it, so start with the ones who lose nothing: GST-registered customers can claim it back on their own returns. IRAS accepts two ways of documenting it. Issue credit notes cancelling the original invoices and re-issue tax invoices with GST. Or, where a customer received several invoices in the period, issue one tax invoice showing only the GST and listing the original invoice numbers.
Build the backdated returns from the books
Output tax is 9% on top where the customer pays and 9/109 of the amount received where you absorb it. Against it goes input tax on your own purchases from the backdated date: tax invoices addressed to you, blocked items such as motor cars left out. Goods bought earlier and still held on that date, and rent, utilities and services from the six months before it, can qualify under the pre-registration rules. IRAS publishes a checklist for those claims; complete it and keep it.
If you cannot pay at once, ask before the due date
IRAS says it may allow the GST for the backdated period to be paid in instalments. Ask while the tax is not yet overdue. Unpaid GST carries a 5% penalty, and a further 2% a month once it is more than 60 days late.
Then make it impossible to repeat.
Three habits are enough. Keep a calendar-year total of taxable turnover in the monthly close, beside the financial-year one. Run the retrospective test in the first week of every January and file the computation, whichever way it comes out. And check the next twelve months on the day any large contract, quotation or tender is signed. The next fixed date is 31 December 2026: if this year’s taxable turnover is above S$1 million, the application is due by 30 January 2027.
Common questions.
What is the penalty for late GST registration in Singapore?
IRAS backdates the registration to the date the business should have been registered, and GST is payable on every taxable sale from that date, whether or not it was collected from customers. On top of that, late notification can bring a fine of up to S$10,000 and a penalty of 10% of the GST due, and prosecution may apply. If the business applies for registration and discloses the lateness itself, before IRAS queries it, IRAS will generally waive the fine and the penalty. The backdated GST is still payable.
Will IRAS waive the backdated GST if I come forward voluntarily?
No. IRAS states that the backdated registration date and the backdated tax cannot be waived, because GST is self-assessed and monitoring turnover is the business's responsibility. What voluntary disclosure generally removes is the late-notification fine and penalty. If paying the backdated GST at once is difficult, IRAS may allow instalments.
How is the GST on past sales calculated if I never charged it?
If a customer agrees to pay the GST now, it is 9% on top of the original price and the customer funds it. If not, the amount already received is treated as GST-inclusive and the tax is 9/109 of it, about 8.26%. On S$700,000 of sales that is S$57,798 if nothing is recovered. Input tax on the business's own purchases from the backdated date is claimed in the same returns, subject to the usual conditions.
Can I recover backdated GST from my customers?
Yes, if they agree to pay it. GST-registered customers can claim it as input tax if they meet the usual conditions, so most have little reason to refuse. IRAS accepts two ways of documenting it: issue credit notes cancelling the original invoices and re-issue tax invoices with GST, or issue one tax invoice showing only the GST and referring to the original invoice numbers, a concession where several invoices went to the same customer in the period. Customers who are not GST-registered cannot claim it back and are harder to ask.
When exactly must a business register for GST?
Under the retrospective view, when taxable turnover for the calendar year exceeds S$1 million: apply between 1 and 30 January, and registration takes effect on 1 March. Under the prospective view, when you can reasonably expect taxable turnover to exceed S$1 million in the next 12 months and have evidence such as signed contracts or accepted quotations: apply within 30 days after the date of the forecast. For liabilities arising on or after 1 July 2025, registration takes effect two months after that date.
My turnover passed S$1 million in the middle of the year. Must I register immediately?
Not on that fact alone. If you do not reasonably expect taxable turnover to exceed S$1 million in the next 12 months, IRAS does not require immediate registration: you test on 31 December and, if the calendar year exceeded S$1 million, apply by 30 January. If signed contracts or confirmed orders make the next 12 months certain to exceed S$1 million, the prospective view applies and you have 30 days from that date.
Do export sales count towards the S$1 million threshold?
Yes. Taxable turnover includes zero-rated supplies, such as exports of goods and international services, alongside standard-rated sales. It excludes exempt supplies, out-of-scope supplies and the sale of capital assets. A business whose taxable supplies are more than 90% zero-rated, and which would be in a net refund position if registered, can apply to IRAS for exemption from registration.
Can I split my business into two companies to stay under S$1 million?
Not if avoiding registration is the purpose or the effect. IRAS says it may disregard the arrangement and register the whole business from the date it became liable, with GST payable on all sales from that date. Separately, a sole proprietor must combine the turnover of all their sole-proprietorship businesses with any income from a trade, profession or vocation, and partnerships with the same partners are combined.
Can I cancel my GST registration if turnover falls back below S$1 million?
You can apply to cancel once you are no longer liable: you do not expect the next 12 months to exceed S$1 million. If the last calendar year was above S$1 million, IRAS also expects the drop to come from a specified circumstance, such as a major contract ending or a large-scale downsizing, and a projection you can substantiate. A business that registered voluntarily must stay registered for two years. On cancellation, GST must be accounted for in the final return on business assets still held if input tax was claimed on them and they are worth more than S$10,000 in total.
Official sources
The registration tests, the exceptions, the consequences of late notification, recovery from customers, pre-registration claims, exemption, cancellation and late-payment penalties as published by IRAS on the pages below; the tax fraction from paragraph 5.5 of IRAS’s GST General Guide for Businesses; the two audit cases from an article IRAS contributed to the Institute of Singapore Chartered Accountants in October 2025. All checked on 30 September 2026. The events company and every figure in its bill are illustrative.
- IRAS: Do I need to register for GST (tests, exceptions and late notification)
- IRAS: Applying for GST registration
- IRAS: Voluntary disclosure of errors for reduced penalties (GST)
- IRAS: Claiming GST incurred before GST registration
- IRAS e-Tax Guide: GST General Guide for Businesses (value of supply and the tax fraction)
- IRAS: Applying for exemption from GST registration
- IRAS: Responsibilities of a GST-registered business
- IRAS: Cancelling GST registration
- ISCA: Understanding GST registration obligations (contributed by IRAS, October 2025)
This guide provides general information, not accounting, tax or legal advice. The events company and its figures are illustrative. Whether and when a business is liable to register, what IRAS waives and what can be claimed depend on its own facts; GST rules are as published on the date shown and change from time to time.
WRITTEN BY
Jacqueline May
Principal Accountant · Chartered Accountant (Singapore), in practice since 2008
Jacqueline is a Chartered Accountant (Singapore) and the Principal Accountant at Synergy Accounting, in practice since 2008. She works on corporate tax, GST and ACRA compliance for small and medium businesses — the filings, deadlines and judgement calls most owners would rather hand over. These guides are written from what she sees in practice.