The Unique Taxpayer Reference (UTR) is a 10-digit number issued by HMRC for self-assessment taxpayers, companies, partnerships, and trusts.

What's the difference between UTR and NINO?

NINO (National Insurance Number) is for employment and state benefits. UTR is specifically for tax purposes and self-assessment. Individuals may have both.

How do I validate a National Insurance Number?

A valid NINO has the format: 2 letters, 6 digits, 1 letter (A, B, C, or D). Certain letter combinations like BG, GB, NK, KN, TN, NT, ZZ are invalid.

Format guidance · Verified checks when available

United Kingdom TIN validator

Review the expected United Kingdom UTR / NINOstructure before you save it, send it to an API, or include it in a tax workflow. Interactive validation appears only after this country's rules pass authoritative-source verification.

Private by design

Transient validation, no public history

TINs are sent securely to the canonical validation API, processed in real time, and not persistently stored by the public checker.

How United Kingdom tax IDs are formatted

In United Kingdom, the tax identifier is commonly known as Unique Taxpayer Reference / National Insurance Number (UTR / NINO). The expected format is UTR: 10 digits, NINO: 2 letters + 6 digits + 1 letter (e.g. AB 12 34 56 C). Teams usually need a United Kingdom UTR / NINO check around self-assessment tax return, employment, state benefits, or before a record moves into billing, onboarding, or compliance review.

Valid examples

AB 12 34 56 C
1234567890

Invalid examples

AB 12 34 56 (Missing suffix)
123456789 (Too short)

What this page covers

Format details below are guidance from public sources. Automated pass/fail results are offered only when the backend catalog marks this country as verified syntax.

Format and length

Confirms the number follows the expected United Kingdom pattern: UTR: 10 digits, NINO: 2 letters + 6 digits + 1 letter (e.g. AB 12 34 56 C).

Useful examples

Shows valid and invalid-looking samples so you can compare spacing, separators, letters, and digit counts before submitting real data.

Letter placement

Checks letter positions where the UTR / NINO format requires alphabetic prefixes, suffixes, or program identifiers.

When people usually check this number

Self-assessment tax return
Employment
State benefits
Pensions

A format match does not prove that a United Kingdom tax ID belongs to a specific person or business. Use the result as a first-pass data quality check, then confirm sensitive cases with official records.

Official source: HMRC

Last reviewed: May 23, 2026. We update country guidance when public format rules change.

How to check a United Kingdom UTR / NINO

Use this check before a record reaches billing, tax reporting, or manual review.

Enter the UTR / NINO

Paste or type the United Kingdom tax identifier exactly as it appears in your source record. Spaces and separators are fine when they are part of the expected format.

Review the format result

Check whether the number matches the United Kingdom syntax currently implemented here. The result does not query a tax-authority registry or confirm ownership.

Confirm important records

For onboarding, tax reporting, or compliance work, treat the result as a data-quality signal and confirm high-risk records with HMRC or your internal process.

Frequently asked questions

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