How to check an ABN or NZBN
An ABN or an NZBN tells you the legal entity behind a trading name. It does not prove the business is licensed to do the work. Check the licence as well.
Look up the number yourself. A screenshot in a quote can be cropped.
Australia
Search the Australian Business Register. Check the entity name, whether the ABN is active, and the goods-and-services tax status if the quote talks about GST. The name on the invoice should match the entity you looked up, or the quote should explain the trading name.
New Zealand
Search the New Zealand Business Number register for the entity you are contracting with. A trading name can sit on top of a company. The invoice should make that plain.
What a match does not prove
An active number does not mean the business is licensed, insured, or the right trade for your job. It also does not mean a website review is real. Pair this check with the licence registers and a written scope.
Common questions
The ABN is active but the name is different. Is that a problem?
Ask them to explain it in the quote. You want the contracting party to be the entity you looked up, or a clearly named trading name of that entity.
Does GST registration change the quote?
If GST applies, the quote should say whether the total includes it. The register shows status. It does not calculate the invoice for you.