Supplier charged GST but ABN Lookup says unregistered?

Start with the purchase that raised the question. It doesn't assume that a supplier has done anything dishonest: the invoice might name an old entity, contain a mistyped number or relate to a period when registration was active.

Match the number to the entity that supplied you

Use the Australian business number (ABN) printed on the invoice, rather than relying on a name search. ABN Lookup shows public entity and GST details. Compare the legal entity, trading name where available and registration dates with the contract or order.

An active ABN and GST registration are different facts. Likewise, a company number isn't an ABN. If the invoice contains a number that belongs to a different entity, ask which entity made the supply and request corrected paperwork. Don't resolve the discrepancy by substituting a number you found online.

Check the dates, not just today's status

Open the historical details available for the ABN. Record the purchase or supply date, invoice date, GST registration periods and the date you ran the lookup. A cancellation after a transaction doesn't automatically invalidate the earlier period. A present-day registration doesn't prove the supplier was registered when the transaction occurred.

If a supplier says a registration is being backdated, retain that explanation but leave the issue open until it is supported. Whether a supplier was required to register and how an incorrect GST charge is dealt with can require an agent's assessment of the facts.

Invoice field	Record to compare	Action
Supplier: Example Workshop	Legal entity on the order and ABN record	Ask who made the supply if the names differ
ABN: not reproduced in this example	Exact 11-digit number on the actual invoice	Avoid selecting a similarly named business
Invoice date: 12 August	Supply date and historical GST registration periods	Record the relevant dates, not just today’s status
Price: $1,000 plus $100 GST	Taxable supply and registration evidence	Keep $100 unresolved while the mismatch is checked
Lookup checked: 7 September	Saved result or dated note	Attach supplier response and corrected document

The invented supplier is not a claim about a real business. An ABN lookup is evidence to investigate, not a complete tax ruling. Original ASBG worksheet; all example figures are fictional.

Ask for a specific correction

A useful request reads: "Invoice W-25 shows $100 GST. The ABN on the invoice currently shows no GST registration. Could you confirm the entity that supplied the work and its GST registration for the supply date? If GST was charged incorrectly, please send corrected documents and explain the refund or credit."

The ATO's registration guidance says an unregistered supplier that incorrectly charges GST should reissue the invoice and refund the GST. Complicated cases, including backdated registration or excess GST already reported, need review. Don't assume that every mismatch is solved by claiming the displayed amount anyway.

Where the invoice remains incomplete, the missing-invoice process explains the document requirements. Keep the original invoice alongside the correction; replacing the attachment without a note loses the audit trail.

Keep withholding and GST questions separate

"Not registered for GST" is different from "has not quoted an ABN". The no-ABN withholding rules have their own conditions and exceptions. Don't withhold an arbitrary percentage merely because GST registration is absent. If an ABN is missing or appears invalid, ask your agent to check that separate obligation before paying.

If you already claimed the disputed GST, show the agent the original invoice, lookup evidence, supplier response and BAS reference. The ATO treats incorrectly charged GST separately from ordinary GST errors; a refund or correction route depends on the circumstances.

Close the invoice record

Record the final GST decision, corrected invoice reference and any supplier refund. Match a refund to the original purchase rather than treating it as new sales. If the supplier provides no satisfactory answer, keep the dispute and potential credit visible for the agent rather than marking it "done".

Continue with the next question

• Missing tax invoice? Check the evidence before claiming GST
• GST on overseas software: check the subscription invoice

Key takeaways

• Match the exact ABN, supplier entity and transaction date.
• Save historical registration evidence and the supplier's explanation.
• Resolve the tax and paperwork questions before assuming a credit.

Where to get help

Use ABN Lookup for the public record and a registered agent for unresolved entitlement or withholding questions. See Bookkeeping and BAS for the wider purchase-record process.