GST Registration Check Singapore: How to Verify a Company

A supplier hands you an invoice with 9% GST on it. Your accounts team is about to pay. One quick check tells you whether that GST line is real, whether the supplier is entitled to charge it, and whether you can claim it back as input tax. Skip the check and you can end up paying GST you can't recover, or holding an invoice IRAS will not accept.

This guide walks through the exact IRAS search to run before you approve a supplier or accept an invoice, what each result means, and what to do when the numbers don't line up. We handle quarterly GST F5 filings for our clients every quarter, so we've seen most of the ways this goes wrong.

How to check a company's GST status on the IRAS portal

IRAS runs a free, public service called the GST Registered Business Search. You do not need a myTax Portal login. This is the only authoritative source, so use it directly.

Direct URL: https://mytax.iras.gov.sg/ESVWeb/default.aspx?target=GSTListingSearch

Here's the five-step check:

1. Open the IRAS GST Registered Business Search page.
2. Enter one business name, or up to four tax reference numbers at once (UEN, GST registration number, or NRIC for sole proprietors).
3. Complete the CAPTCHA if displayed.
4. Click Search.
5. Compare the result against the supplier's legal name, UEN, GST number, and the invoice date.

Save or print the search result and file it with the invoice, especially for material purchases. A dated screenshot is the cleanest supporting document if IRAS ever queries your input tax claim.

The search returns:

• Registered name of the business.
• GST registration number (or tax reference number).
• UEN, where applicable.
• GST registration status.
• GST registration effective date.
• GST de-registration date, where relevant.

The search works best when you use the UEN or GST registration number rather than a partial business name. A result is evidence of the entity's status on IRAS's database only; it does not validate the invoice amount or the identity of the person who issued the invoice.

What a Singapore GST registration number looks like

A Singapore GST registration number takes one of two forms. For many businesses it is the same as the entity's UEN. For others, IRAS issues a separate GST number, usually starting with "M". IRAS's own invoicing guidance gives the example of a business with UEN 123456789A and GST registration number M21234567K. Both are legitimate.

When the GST number is the UEN, it follows the UEN format for that entity type:

So a GST number that differs from the supplier's UEN on ACRA's Bizfile is not a red flag on its own. What matters is that the IRAS search returns the supplier's legal name against the exact number printed on the invoice.

Do not guess a GST number from the invoice. Search the exact number the supplier gave you, and confirm the legal name matches. For the mechanics of what UEN characters mean, our UEN numbers in Singapore guide has the full breakdown.

How to read the search result

The status field answers the question "should this supplier be charging me GST?"

The effective date is the field most SME finance teams miss. Check the supplier's status as of the date of supply, not the day your accounts team runs the search. A supplier can have been registered when it invoiced you in March and de-registered by October. Same company, same UEN, different tax treatment.

A "Registered" result does not automatically mean every line on the invoice should bear 9% GST. Standard-rated supplies do; zero-rated, exempt, and out-of-scope supplies do not.

What a valid GST tax invoice must contain

A registered supplier still has to issue a compliant tax invoice for you to claim input tax. IRAS's Invoicing Customers guidance sets out the required contents. For a full tax invoice, check:

1. Supplier's name, address, and GST registration number.
2. Invoice number and invoice date.
3. Customer's name and address.
4. Description of the goods or services.
5. Quantity or extent of the supply.
6. Amount payable excluding GST.
7. GST rate and GST amount, shown separately.
8. Total amount payable including GST, and the currency if not SGD.

Where the total payable (GST included) does not exceed S$1,000, a simplified tax invoice is allowed. It carries less information: supplier name, GST number, date, description, and GST-inclusive total. Anything above S$1,000 needs the full tax invoice.

Common gaps are a missing GST number, GST not shown separately from the net amount, or the invoice using a trading name rather than the registered legal name. Ask for a corrected invoice before you claim.

When a company must be GST-registered

For a Singapore business, compulsory GST registration kicks in when taxable turnover exceeds S$1 million under either of two tests.

The prospective test catches businesses that sign a large contract or land a major tender they can already see will breach S$1 million. You do not wait for invoices to be issued. Once you have objective evidence, you have 30 days to apply. Since 1 July 2025, IRAS registers you 2 months from the forecast date (previously the 31st day), which gives you time to set up GST invoicing before you start charging it.

The S$1 million test is on taxable turnover, not every receipt. Standard-rated and zero-rated supplies count. Exempt supplies, non-business receipts, and connected-business rules can change the calculation. IRAS's Do I need to register for GST? page has the full rulebook.

If your business is nowhere near S$1 million but you want to register anyway, our voluntary GST registration guide covers when it pays off and when it locks you into two years of compliance for no gain.

Registering also brings an e-invoicing obligation: new voluntary GST registrants must send their invoice data to IRAS through InvoiceNow from 1 April 2026, and the requirement is phased in for the remaining GST-registered businesses from 1 April 2028 to 1 April 2031. Our GST InvoiceNow guide covers what that involves.

What to do if a supplier's GST number doesn't verify

Here's the sequence when a check comes back "Not Registered" or the details don't match:

1. Recheck the number for transcription errors. A single missing letter flips the result.
2. Search again using the supplier's UEN and legal name.
3. Cross-check the supplier's UEN on ACRA Bizfile. The GST search confirms status; Bizfile confirms the UEN belongs to the entity issuing the invoice. Both records should tie together.
4. Compare the IRAS and Bizfile results with the invoice.
5. Ask the supplier to explain and, if needed, to reissue the invoice.
6. Hold the GST portion of the payment until the mismatch is resolved.
7. If the supplier still insists on charging GST despite being unregistered, contact IRAS.

Keep the search screenshot, the invoice, and any correspondence together in your accounting file. That paperwork is what protects you if IRAS asks how you satisfied yourself the input tax claim was valid.

Can I claim input tax if my supplier isn't GST-registered?

Generally, no. Input tax is not claimable just because an invoice has a GST line on it. To claim, you must hold a valid tax invoice from a GST-registered supplier, and the purchase must meet the standard input tax conditions under the GST Act.

If a supplier who is not registered has charged you an amount labelled "GST", the correct fix is a credit note and a corrected invoice, not a claim. Claiming risks:

• Disallowance of the input tax claim.
• Repayment of the wrongly claimed GST.
• Interest and penalties on the wrongly claimed amount.
• Adverse findings on your record-keeping if IRAS audits.

If your business is GST-registered, build this into your accounts payable process: no verified IRAS status, no input tax claim. On Xero, that can be a flag on any bill from a new supplier as "GST verification required" until the check is done.

For larger AP teams processing many invoices, IRAS also publishes a Check GST Register API that lets your accounting or ERP system check status by GST number, UEN, or NRIC.

Penalties for late GST registration or fake invoices

For late notification of GST registration liability, IRAS states that you may face:

• A fine of up to S$10,000.
• A penalty equal to 10% of the GST due.
• Prosecution action, in some cases.

IRAS will also backdate your registration to the date you ought to have been registered. You then have to account for and pay GST on past sales from that date, even if you did not collect any GST from your customers, so the GST comes out of your margin. The one piece of good news: if you apply and voluntarily disclose that you are late, IRAS will generally waive the late-notification fine and penalties.

For fake or fraudulent GST invoices, exposure is more serious. A person who knowingly issues a false, forged, or fraudulent invoice may face prosecution under the GST legislation, with fines, imprisonment, recovery of the tax loss, and penalties on any incorrect returns filed. The exact penalty depends on the offence, so treat any suspected fake invoice as a matter to escalate rather than absorb.

If you receive an invoice you suspect is fake, preserve the invoice, correspondence, payment evidence, and IRAS search record. Do not claim the GST, and consider getting tax or legal advice before responding to the supplier.

Frequently asked questions

Is a UEN automatically a GST number?

No. A UEN identifies the entity; it does not prove the entity is GST-registered. A company can hold a UEN for years without registering for GST. Always confirm through the IRAS GST Registered Business Search.

Can a supplier charge GST before its GST registration is approved?

Generally, no. A business should not charge GST as a registered supplier before its effective registration date. Anything invoiced before that date should not carry a GST line.

Does a "GST" line on an invoice prove the supplier is registered?

No. Anyone can type "GST" onto an invoice. Verification is the buyer's job, and the only reliable source is IRAS's search.

Can I claim input tax from an unregistered supplier?

Generally, no. Even if the invoice shows a GST amount, you can only claim input tax when the invoice is a valid tax invoice from a GST-registered supplier.

What if the IRAS result does not match the invoice?

Stop and resolve the mismatch. Check the legal name, UEN, GST number, invoice date, and registration effective date. Request a corrected invoice, and hold the GST portion of the payment until the discrepancy is cleared.

What if a supplier's GST number starts with "M"?

That is a normal IRAS format. Some businesses have a GST registration number that differs from their UEN, and these usually start with "M" (IRAS's example is M21234567K). Search the exact number in the IRAS GST Registered Business Search and confirm the legal name matches the invoice.

Get your GST filings running clean

A supplier check that takes 60 seconds prevents an input tax claim that can take months to unwind. If you'd rather not run these checks in-house every quarter, our GST filing service covers registration, quarterly F5 submissions, supplier due diligence, and InvoiceNow setup on Xero. Book a free consultation and we'll take GST off your plate.