Subcontractor ABN checks for builders: when to check, what to look at, and keeping it up all year
Most builders check a subbie once, when they first set them up, and never again. But an ABN can be cancelled, a GST registration can end and a business can change its entity part way through a job, and none of that shows up in your accounting software. Building and construction is one of the industries in the ATO's taxable payments reporting system, so every subbie's ABN and name end up in the TPAR you lodge by 28 August. This page sets out the register checks that matter and a simple routine for keeping them current. It's general information only.
The three checks on the register
ABN status. ABN Lookup shows whether an ABN is Active or Cancelled and the date that status took effect. A cancelled ABN can still pass the checksum, so a quick format check won't catch it.
GST registration. An ABN and GST registration are separate. A subbie can hold an active ABN without being registered for GST, and the register records the dates a registration started and ended. If a subbie's invoices add GST, the registration should be current on the invoice date.
Registered name. The name on the invoice should match the entity name or one of the business names the register shows for that ABN. A mismatch often means the subbie trades through more than one entity, such as a company and a trust, each with its own ABN.
When to check
When a subbie starts: get their ABN in writing (a new supplier form helps), look it up, and save the entity name the register shows rather than the trading name on their ute.
Before you pay a claim from a subbie you haven't used in a while, or when the ABN or name on an invoice doesn't match what you have on file. The ATO's advice on its TPAR contractor details page is to check that the ABN on each invoice matches the ABN on file, create a new contractor record when it doesn't, and confirm the ABN, name and GST registration on ABN Lookup or in the ATO app.
In July, before the TPAR: run the whole contractor list once more so cancelled ABNs, ended GST registrations and changed names are fixed before the report is built.
If a subbie has no ABN
The ATO's guidance is that when a supplier doesn't quote an ABN and the payment is more than $75 excluding GST, the payer generally withholds the top rate of tax (47%), unless an exception applies. The ATO pages linked below explain the exceptions, and ClearABN's no-ABN withholding calculator works out the amount.
Checking the whole list at once
ABN Lookup checks one ABN at a time. Export your contractor contacts from Xero, MYOB or QuickBooks and upload the file to ClearABN instead: every row gets the ABN checksum and a register lookup for status, entity and business names, and GST registration. The first 25 rows of each file are free, with no account.
Rows come back flagged when the ABN is missing, fails the checksum, is cancelled, isn't on the register, has no current GST registration, or the name doesn't closely match. You also get a dated PDF of what the register showed, which is worth keeping with the job file.
Keeping it checked between TPARs
On a Monitoring plan, contractor watch saves your subbie list and re-checks every ABN on the register each month, and emails you if a subbie's ABN is cancelled, their GST registration ends or their registered name changes. To keep an eye on just one subbie, the free ABN watch covers one ABN per email address, with no account.
General information only
This page summarises published ATO guidance and what the Australian Business Register shows. It isn't tax advice, and it doesn't cover licences or insurance, which are separate checks. Whether you need to lodge a TPAR, withhold from a payment or claim a GST credit depends on your circumstances: read the ATO pages below or ask a registered tax or BAS agent.
Related
Check your supplier list now
Free for 25 suppliers per check. No account required.
Official sources
ClearABN shows Australian Business Register facts and the result of an ABN checksum. It does not provide tax, legal or financial advice. Links go to the ATO and the Australian Business Register so you can read their pages yourself.