Verify Supplier UEN & GST Before Paying an Invoice (Singapore)

Before paying a Singapore supplier invoice, AP should verify the UEN in BizFile, confirm GST registration in IRAS for the invoice date, and keep dated evidence with the supplier record. The four checks are:

1. The UEN exists in BizFile — the entity behind the invoice is a real, registered business and the registered name matches what the invoice shows.
2. The GST registration is active as of the invoice date in IRAS's myTax Portal GST Registered Business Search — not just registered today, but registered on the supply date.
3. The registration is not de-registered or suspended at the supply date — a previously registered supplier may have lost status since you last paid them.
4. The registered principal activity is consistent with the invoice line — a registered cleaning-services supplier billing you for IT consulting is a flag worth documenting, even if it is not necessarily fraud.

The effective date is the usual failure point. BizFile answers whether the entity exists; IRAS answers whether it was GST-registered on the supply date. A S$10,000 invoice dated 1 March 2026 from a supplier whose GST registration effective date is 15 April 2026 carries S$900 of GST that is not claimable as input tax, even if the supplier printed a registration number on the invoice.

This buyer-side workflow assumes the UEN and GST number are already on the invoice. For issuer-side fields, see the guide to 11 mandatory fields a Singapore tax invoice must carry. For foreign suppliers with no Singapore GST charged, see reverse charge for imported services from foreign suppliers.

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Check 1 — UEN Exists in BizFile, and the Format Sanity-Check Before You Look

BizFile (bizfile.gov.sg) is the entity-existence register run by ACRA. A BizFile UEN search returns the registered entity name, the entity type, the registration date, and the current status — live, struck off, dissolved, in liquidation, and so on. That is what answers check 1: the UEN belongs to a real entity, the entity is currently in good standing, and the registered name lines up with what the invoice says the supplier is called.

Before you open the portal, the UEN itself often tells you whether the search will return anything. Singapore UENs come in three formats, each tied to entity type, and any AP clerk who reads enough invoices learns to spot a wrong one at a glance.

• 9-character format (nnnnnnnnX) — ACRA-registered businesses such as sole proprietorships and partnerships, and the older numbering still carried by some long-established entities. Eight digits and a check letter.
• 10-character format (yyyynnnnnX) — local companies registered before 2009, where yyyy is the year of incorporation, nnnnn is the serial number, and X is the check letter. A Pte Ltd incorporated in 2005 will look like 200512345A.
• 10-character format (TyyPQnnnnX) — every other entity issued from 2009 onward. T represents the 2000s, yy is the year, and PQ is the entity-type code: LL for an LLP, LP for a limited partnership, FC for a foreign company branch, CC for a charity, SS for a society, and so on. An LLP formed in 2018 looks like T18LL1234A.

That three-format guide turns the UEN into a first-pass red flag. A Pte Ltd whose UEN starts with T-yy-LL is not a Pte Ltd. An LLP that hands you a 9-character UEN with no entity-type code is not an LLP. Wrong character count, an entity-type code that contradicts how the supplier presents itself, or a string that does not parse to one of the three formats above is almost always a typo on the invoice and occasionally something that warrants a phone call before you spend time on the IRAS lookup.

For a new supplier going onto the master, the BizFile search is part of onboarding alongside the IRAS check. Run both, save the BizFile screenshot with the date of the lookup, and store it against the supplier record. The audit value of the check sits in being able to produce that record on demand, not in remembering you did the search once two years ago. When BizFile returns the entity, also note what it says under registered principal activity — that is the field check 4 will compare against the invoice line, and capturing it now avoids re-running the search later.

Checks 2 and 3 — IRAS GST Status, Effective Dates, and De-Registration

The IRAS myTax Portal GST Registered Business Search is the GST-registration register. It sits at mytax.iras.gov.sg, requires no login, and accepts a lookup by UEN or by registered name. The result returns the GST registration number, the registered name, the GST registration effective date, and — when applicable — a de-registration date. Those four fields are the entire output, and they are enough to verify GST registration number against what the supplier printed on the invoice and to read the effective date against the invoice date.

The reading you need to do is mechanical, but the conclusions matter. Three combinations come up in practice:

• Effective date on or before the invoice date, no de-registration date. The supplier was a registered taxable person on the supply date. The GST line is supportable for input tax provided the rest of the invoice (the issuer-side fields, the underlying supply) holds up. This is the case AP wants to see.
• Effective date after the invoice date. The supplier was not registered on the supply date. Any GST charged on the invoice is unrecoverable input tax — IRAS will not allow it on your GST F5, regardless of what the registration number printed on the invoice shows.
• De-registration date present and on or before the invoice date. The supplier had de-registered by the supply date. Any GST charged is similarly unrecoverable, and the invoice should have been issued without GST in the first place.

The opening worked example is the canonical case for the second combination. A S$10,000 invoice dated 1 March 2026 from a supplier whose IRAS effective date is 15 April 2026 carries S$900 of GST that the AP team cannot claim. Save the IRAS screenshot, time-stamped, against the supplier record. The operational response — what to pay, what to hold, how to handle a supplier who insists the registration was active — sits in the failure-mode section further down, because the same default applies whichever of the four checks fails.

One note on the GST registration number itself. A registration number printed on the invoice is evidence the supplier claims to be registered; it is not a check. The number can be valid in format and still belong to a supplier whose registration was effective only after the invoice date, or whose de-registration date precedes the invoice. The lookup is what confirms the GST registration number against status and effective date — the field on the invoice does not.

Save the IRAS result against the supplier record with the lookup date. That dated record is the evidence supporting the input-tax claim.

Onboarding-time verification is only a snapshot. Run quarterly re-checks around the GST F5 cycle and look for new de-registration dates or status changes. When a de-registered supplier is still charging GST, and the IRAS de-registration date falls on or before the invoice date, stop accepting GST on new invoices with that UEN, request a revised invoice without GST, and keep the earlier audit evidence for periods when registration was active.

Suspension is rarer than de-registration but works the same way for AP purposes. GST charged during a suspension window is not supportable for input tax until the supplier produces evidence the suspension has been lifted. For high-value or recently registered suppliers, spot-check each invoice until the risk settles.

Check 4 — Does the Registered Activity Match the Invoice Line

BizFile records each entity's registered principal activity, typically as an SSIC code with a short description (62012 — Information technology consultancy services, 81211 — General cleaning services of buildings, and so on). Check 4 asks whether the invoice line items fit that activity.

Mismatch is not the same as fraud. Legitimate suppliers expand into adjacent activities, and some Pte Ltds carry broad principal activities such as "holding companies" or "business and management consultancy". The standard AP response is to document the mismatch, ask the supplier to confirm the work was performed, and escalate only when the gap is wide, the invoice value is high, or the mismatch stacks on top of other supplier flags.

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When a Check Fails — The AP Team's Response

The default response when any of the four checks fails has the same shape: do not approve the GST line, document the failure with the supporting register screenshot and a dated note, and request a revised invoice from the supplier that reflects the actual position. The detail differs by check.

Failed check	Payment response	Evidence to keep
UEN does not resolve in BizFile	Hold the invoice until the supplier confirms the correct UEN and reissues the document. Do not guess a similar UEN.	BizFile search result, supplier correction, revised invoice.
GST registration was not active on the supply date	Hold the GST line, pay the net amount only if the supply itself is valid, and request a revised invoice without GST. If the supplier disputes the result, ask for their IRAS print-out and re-run your lookup.	IRAS result, dated note, supplier correspondence, revised invoice.
Activity does not match the invoice line	Document the mismatch and ask the supplier to confirm the work. Escalate only where the value, mismatch, or stacked flags justify it.	BizFile result, AP note, supplier confirmation, escalation decision.

Xero, MYOB, and QuickBooks SG can store supplier UEN and GST registration numbers, but they do not enforce IRAS effective-date matching at payment time. The check is operational, not automatic.

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Verifying at Scale — The 4-Entry IRAS Cap and the Quarterly Bulk Check

Single-invoice verification scales linearly with the AP team. Supplier-master verification does not, because the IRAS GST Registered Business Search currently caps the single-search form at four UENs at a time.

Use the scale of the supplier master to choose the route:

• Low hundreds: manual quarterly myTax Portal checks, scheduled around GST F5 preparation.
• Thousands: a paid supplier-data feed that includes UEN existence, entity status, and GST-registration status.
• InvoiceNow or AP platform validation: useful for current counterparty checks at intake, but still retain invoice-date IRAS evidence for GST claims.

Whichever route you take, the data prerequisite is the same: a clean ledger of supplier UENs, GST registration numbers, and the invoice dates and totals they have appeared on. AP teams that maintain that ledger as a structured artefact — even a spreadsheet, updated as invoices arrive — can run a quarterly verification cycle in an afternoon. AP teams that do not end up reconstructing it from a folder of PDFs every cycle, which is where the cadence quietly slips.

Converting the supplier-invoice corpus into that ledger up front is what makes the bulk verification viable in the first place. Pulling supplier UEN, GST registration number, vendor legal name, invoice date, GST amount, and total out of a heterogeneous bundle of supplier PDFs into a single structured spreadsheet is exactly what our AI invoice data extraction for Singapore AP teams is built to do — describe the fields you need, upload the batch, and download an Excel, CSV, or JSON file that feeds straight into the IRAS lookup or a commercial verification feed. Retail-leaning supplier books that mix tax invoices with simplified receipts and delivery notes need the same upstream consolidation step before any verification cycle runs, and the GST-aware Excel intake for Singapore retail invoices, receipts, and delivery notes walks that mixed-document case in detail. The product is the upstream extraction step, not the verification tool itself; the verification is yours to run against IRAS and BizFile.

For AP teams whose remit covers more than Singapore, the same control runs in adjacent jurisdictions with different registers and different failure modes — the Australian ABN verification workflow for the same AP control is the closest structural sibling and worth reviewing if your shared-service centre processes both.

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The Knowledge Principle — Why the Four Checks Are Audit Defence, Not Hygiene

Since 1 January 2021, IRAS has applied the Knowledge Principle: input tax is denied, with a 10% surcharge on top, for any supply the buyer knew or should have known formed part of a Missing Trader Fraud arrangement. That standard makes supplier verification an audit-defence control, not a filing preference.

IRAS's conditions for claiming input tax require local purchases to be supported by a valid tax invoice, and the supplier's GST registration status is central to the claim. The same records support GST F5 review: BizFile and IRAS screenshots, dated notes, supplier correspondence and any revised invoices. For the quarter-end side, see the companion piece on reconciling Box 5 and Box 7 on the GST F5 from supplier invoices.

UEN and GST verification is only the baseline layer of MTF defence. Chains of related entities, payment patterns that do not match the underlying supply, and missing-supply indicators sit beyond the four checks here; the Singapore Missing Trader Fraud AP due-diligence checklist covers that deeper layer. The goal of this workflow is simple: when IRAS, the external accountant, or the finance lead asks why GST was paid and claimed, AP can produce the record instead of reconstructing it after the fact.