South Africa
Your VAT number on South African invoices: format and checks
Where your VAT registration number goes on a South African tax invoice, its 10-digit format starting with 4, the check digit, and when to show your client's number.
Last updated · Invoice Native team
Your VAT registration number is what marks an invoice as a tax invoice, and your VAT-registered clients rely on it for their own VAT records. Section 20 of the VAT Act requires it on every tax invoice, full or abridged, and section 21 requires it on credit and debit notes.
This guide covers where the number goes, what a valid one looks like, the check digit that catches typos, and when you also need your client's number. The free invoice generator checks your VAT number as you type and prints it under your name.
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Where your VAT number goes
Put your VAT number near your name and address at the top of the invoice, where your client's accounts team expects it. Common labels are:
- VAT No.
- VAT Reg No.
- VAT Registration No.
SARS's own examples use "VAT Registration No." and "VAT No.". Any clear label works. Invoice Native prints "VAT No. 4321123459" under your business name.
The same number must appear on:
| Document | Your VAT number | Your client's VAT number |
|---|---|---|
| Full tax invoice | ✔ | ✔ if your client is a vendor |
| Abridged tax invoice (to R5,000) | ✔ | — |
| Credit note or debit note | ✔ | ✔ if a vendor, unless the original was abridged |
| Invoice when not registered | — | — |
The format: 10 digits starting with 4
A South African VAT registration number is 10 digits and starts with 4. It has no letters, spaces or dashes. If a number your client gives you is nine digits, starts with another digit or has letters in it, ask them to check it.
Don't confuse it with your other numbers:
| Number | Format | On invoices? |
|---|---|---|
| VAT registration number | 10 digits, starting with 4 | Required on tax invoices |
| Income tax reference number | 10 digits, starting with 0, 1, 2, 3 or 9 | Not required |
| Company registration number | YYYY/NNNNNN/NN, such as 2021/123456/07 | Required for companies (Companies Act) |
For the company number, see company details on invoices.
The check digit
SARS doesn't publish how VAT numbers are built. But the last digit behaves as a check digit: every real VAT number we've tested passes the standard Luhn (mod 10) check, the same check used on bank cards. It's a quick way to catch a mistyped digit.
To check a number by hand:
- Start from the right. Leave the last digit as it is, then double every second digit moving left.
- If doubling gives more than 9, subtract 9.
- Add up all ten digits.
- If the total divides exactly by 10, the number passes.
For 4321123459, the digits from the right are 9, 5, 4, 3, 2, 1, 1, 2, 3, 4. Doubling every second one gives 9, 1 (from 10), 4, 6, 2, 2, 1, 4, 3, 8. They add up to 40, which divides by 10, so it passes.
A passing check doesn't prove the number is registered to that business. It only shows there's no obvious typo. Invoice Native runs this check as you type and flags a number that fails.
Never copy an example number
SARS's guides use made-up VAT numbers in their sample invoices, and they don't pass the check digit. Don't copy one onto a template "for now" and forget about it. Use your own number from your SARS registration, and check your template before you send the first invoice.
The same goes for numbers in online templates. If a template came with a VAT number already filled in, replace it.
Your client's VAT number
On a full tax invoice, you must show your client's VAT number "where the recipient is a registered vendor". A full tax invoice is required for sales over R5,000 including VAT, and for any zero-rated supply.
Ask business clients for their VAT number when you take them on, and copy it from their own tax invoice or letterhead rather than typing it from memory. If your client isn't a vendor, such as a consumer or a small business below the threshold, leave the field empty. Never put your own number in their place.
Invoice Native asks for the client's VAT number as an optional field and checks it the same way. Because it always prints a full tax invoice, a client's number you add appears on every invoice you send them.
When you're not registered
If you're not registered for VAT, your invoice must not show a VAT number. A business can't charge VAT or call its document a tax invoice until it's registered. See invoicing when you're not registered for VAT.
When you register, switch Invoice Native to "Registered for VAT" and add the number. The title changes to "Tax Invoice" and the VAT column appears. See what a tax invoice must show for the rest of the list.
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Checklist
- ✅ Your 10-digit VAT number, starting with 4, on every tax invoice
- ✅ A clear label: "VAT No." or "VAT Registration No."
- ✅ The number passes the check digit, with no spaces or letters
- ✅ Never an example number from a guide or template
- ✅ Your client's VAT number on full tax invoices when they're a vendor
- ✅ Both numbers on credit notes and debit notes
- ✅ No VAT number at all if you're not registered
Rules can change, so check SARS's guidance or ask a registered tax practitioner about your situation. Invoice Native does not provide tax advice.
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Frequently asked questions
What does a South African VAT number look like?
It's 10 digits long and starts with 4, for example 4321123459. It's printed without spaces or dashes, usually labelled "VAT No." or "VAT Registration No.".
Does every tax invoice need my VAT number?
Yes. Full and abridged tax invoices must both show your name, address and VAT registration number. So must credit notes and debit notes.
When do I need my client's VAT number?
On a full tax invoice, when your client is a registered vendor. An abridged tax invoice, allowed for sales up to R5,000 that aren't zero-rated, doesn't need the client's details.
Can I put a VAT number on my invoice if I'm not registered?
No. A business that isn't registered must not show a VAT number, charge VAT or call its invoice a tax invoice. Never borrow someone else's number either.
Is my income tax reference number the same as my VAT number?
No. The income tax reference number is a different 10-digit number, starting with 0, 1, 2, 3 or 9. It isn't required on invoices, although some suppliers to government show it.
Sources
This guide is general information, not tax or legal advice. SARS and CIPC rules change and depend on your situation, so check sars.gov.za or ask a registered tax practitioner.