How is the NIF check digit calculated?

The first eight digits are weighted by 9, 8, 7, 6, 5, 4, 3 and 2, summed, and reduced modulo 11. The control digit is 11 minus that remainder; if the result is 10 or 11 it becomes 0. The 9th digit must equal this control digit.

Does a valid result mean the NIF really exists?

No. The tool only confirms the format and modulo-11 check digit are correct. A structurally valid NIF is not necessarily one that has actually been assigned, and it is never checked against any tax register.

What does the leading digit of a NIF mean?

The prefix indicates the taxpayer type: 1 and 2 are individuals, 45 a non-resident individual, 5 a company or collective person, and 70/74/75 inheritance or special cases. The tool labels these for you.

What is the difference between a NIF and a NIPC?

A NIF identifies an individual taxpayer, while a NIPC identifies a legal person such as a company. Both are 9 digits and share the same modulo-11 check-digit rule, so this validator handles both.

Is the NIF the same as a Portuguese VAT number?

Yes. A business's Portuguese VAT number is its NIPC/NIF, often shown with the PT country prefix (for example PT123456789) for EU VAT purposes.

Why is the check digit useful?

The check digit catches the most common typing mistakes — a wrong or transposed digit usually fails the modulo-11 test, so validating it before submitting a form avoids rejected paperwork.

Is my NIF sent anywhere?

No. The validator is privacy-first — all processing happens locally in your browser and the number never leaves your device.

Portugal NIF Validator

Portugal NIF validator

Validate a 9-digit Portuguese NIF (Número de Identificação Fiscal) or NIPC. The tool verifies the modulo-11 check digit and identifies the taxpayer type from the leading digit(s) — individual, company, public entity, sole trader and more. It is useful for confirming a tax number was typed correctly before submitting invoices or forms.

How it works

The check digit (the 9th digit) is a weighted modulo-11 checksum of the first eight digits, and the prefix sets the taxpayer type:

weights = 9, 8, 7, 6, 5, 4, 3, 2  (applied to digits 1–8)
sum     = Σ (digit × weight)
control = 11 − (sum mod 11)
if control is 10 or 11 → 0
the 9th digit must equal control

Prefix	Taxpayer type
1, 2	Individual
45	Non-resident individual
5	Company / collective person
70, 74, 75	Inheritance / special

Example

For the NIF 123456789 the first eight digits weighted by 9…2 give a sum whose modulo-11 control digit is computed and compared with the printed 9th digit. A match means a valid check digit, and the leading 1 labels it an individual taxpayer. A single mistyped digit normally breaks the checksum, and the tool shows the expected 9th digit so you can find the error.

It is privacy-first: nothing leaves your browser. The validator only checks the structure and check digit — it does not verify the number against any tax register.