Free calculator
VAT number checker
Type a VAT number to check its format and check digit, right here in your browser. To see whether a vendor is registered, use SARS’s VAT vendor search on eFiling.
10 digits starting with 4
Check
Valid VAT number format
- As printed on an invoice
- VAT No. 4540125707
- Check digit
- Matches
A matching check digit only shows the number is well formed, not that the vendor is registered.
Make a tax invoiceHow a VAT number is checked
A South African VAT number has 10 digits and starts with 4, like 4540125707.
The last digit is a check digit (the Luhn method used for card numbers): from the right, double every second digit, add the digits up, and a valid number’s total ends in 0.
A number that passes is well formed, not necessarily registered — the check only catches typos.
VAT numbers on invoices
- Every tax invoice must show your VAT number.
- A full tax invoice also shows your client’s VAT number when they’re a vendor.
- Without a valid tax invoice, your client can’t claim the VAT back as input tax.
Last updated 2026-10-01. This calculator is a guide, not tax advice.
Frequently asked questions
Does this tell me who a VAT number belongs to?
No. It only checks the number’s format and check digit, offline. SARS’s VAT vendor search on eFiling shows whether a number is registered and to whom.
Why does SARS’s example number fail?
Illustrative numbers such as 4321123450 are made up and don’t have a matching check digit. Real VAT numbers do.
Is my VAT number the same as my income tax number?
No. They’re separate SARS numbers: a VAT number starts with 4, an income tax number usually with 0, 1, 2, 3 or 9.