Verify tax file number checksums.
Initialising algorithm engine for Australian TFN Checksum Validator...
How Australian TFN Checksum Validator Works?
The Australian TFN Checksum Validator works by multiplying the 9 digits of a Tax File Number (TFN) by weights 1, 4, 3, 7, 5, 8, 6, 9, 10 and confirming the sum is divisible by 11.
- 1Remove spaces and confirm 9 digits (older TFNs have 8).
- 2Multiply the digits by 1, 4, 3, 7, 5, 8, 6, 9, and 10.
- 3Add the products.
- 4Mark the TFN valid when the sum mod 11 = 0.
Australian TFN Checksum Validator Formula
The TFN formula is (d₁ + 4d₂ + 3d₃ + 7d₄ + 5d₅ + 8d₆ + 6d₇ + 9d₈ + 10d₉) mod 11 = 0.
S = 1·d₁ + 4·d₂ + 3·d₃ + 7·d₄ + 5·d₅ + 8·d₆ + 6·d₇ + 9·d₈ + 10·d₉ valid ⇔ S mod 11 = 0
dᵢis the i-th TFN digit.
S = 253 253 mod 11 = 0 → valid
Australian TFN Checksum Validator Conversion Table
The TFN validation table lists sample numbers with their weighted sum and result.
| TFN | Weighted sum | Sum mod 11 | Result |
|---|---|---|---|
| 123 456 782 | 253 | 0 | Valid |
| 876 543 210 | 154 | 0 | Valid |
| 123 456 789 | 323 | 4 | Invalid |
| 000 000 000 | 0 | 0 | Valid |
| 111 111 111 | 53 | 9 | Invalid |
Sample numbers are for format testing only. A TFN is confidential, and Australian law restricts its collection and use.
What is Australian TFN Checksum Validator?
An Australian TFN Checksum Validator is a tool that checks the modulus 11 checksum of a Tax File Number issued by the Australian Taxation Office (ATO).
The checksum filters typing errors on tax and superannuation forms before the data reaches the ATO.
What are the uses of Australian TFN Checksum Validator?
There are 3 main uses of the Australian TFN Checksum Validator, including payroll software, superannuation funds, and form validation.
- Payroll software: Payroll systems validate TFNs from TFN declaration forms.
- Superannuation funds: Funds check member TFNs before reporting.
- Form validation: Tax software rejects invalid TFNs on entry.