TFN Check: Test a Number’s Format
Use a local TFN check to spot typing errors, see why an entry fails and distinguish the format test from ATO issuance or identity checks.
Check a nine-digit TFN for typing errors. Older eight-digit entries need separate confirmation.
Enter a number to check
The result will show whether the entry passes the nine-digit format rules.
What a TFN Check Can Confirm
A TFN check tests the number’s format and checksum, a calculation used to detect typing errors. A pass does not prove that the ATO issued the number or that it belongs to the client.
Use the result alongside your practice’s identity checks. For the client-file process, read checking an ABN and TFN.
Why a Number Fails
The checker reports incorrect length and a failed checksum separately. The field accepts only digits and spaces. If you type or paste a letter or other character, the checker removes it, says so below the field and tests the digits that remain. Check those digits against the client’s record before you rely on the result.
An eight-digit entry receives “Eight digits: not checked”. Do not pad it with a zero or treat that result as proof that the number is invalid.
If an entry fails, ask the client to confirm it through your practice’s protected collection process. Do not guess a replacement digit to make the number pass.
Keeping the Number on Your Device
The check runs in your browser. It does not send the entry to Tax Genie, the ATO or another service. It does not save the number in browser storage or the page address.
Select Clear entry to remove the number and reset the result. Leaving or reloading the page also clears it.