TFN Generator
Generate valid, random Australian Tax File Numbers (TFN) that pass the ATO modulus-11 checksum — sample data for testing forms, validators and test suites.
Input
Settings
Output
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/tfn-generator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"count": "5",
"format": "plain"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `tfn-generator` tool (TFN Generator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/tfn-generator/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="TFN Generator — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
What this tool does
It generates random nine-digit numbers that satisfy the Australian Taxation Office's checksum rule for Tax File Numbers. They pass TFN validators, which makes them useful for filling test databases, exercising form validation and writing test fixtures.
They are not real TFNs. They are not issued to anyone, they identify nobody, and using them on an official form is fraud. This tool exists so you don't have to put your own TFN into a staging environment.
How the TFN checksum works
A TFN is valid when each digit is multiplied by its position weight and the total divides evenly by 11.
The weights are:
1, 4, 3, 7, 5, 8, 6, 9, 10So for the TFN 123456782:
(1×1) + (2×4) + (3×3) + (4×7) + (5×5) + (6×8) + (7×6) + (8×9) + (2×10) = 253
253 ÷ 11 = 23 exactly → validThis tool doesn't guess and re-check. It draws the first eight digits at random, then solves directly for the check digit that satisfies the rule. Because the ninth weight is 10, and 10 ≡ −1 (mod 11), the constraint reduces neatly to check digit ≡ sum of the first eight (mod 11). When that lands on 10 there is no single digit that works, so the number is redrawn.
How to use it
Pick how many TFNs you want (up to 50) and whether to format them as plain digits or in the conventional XXX XXX XXX grouping. Click Generate, then copy or download.
Will these pass a real validator?
They'll pass a checksum validator, which is what most software implements. They will not match anything in the ATO's records, and any system that checks against the real register will reject them — as it should.
Privacy
Numbers are generated in your browser. Nothing is sent to a server, and nothing is stored.