Free · Unlimited checks · No signup
United Kingdom TIN validator
Check whether a United Kingdom UTR / NINO follows the expected structure before you save it, send it to an API, or include it in a tax workflow.
Private by design
Your data stays in your browser
None of the TIN data you enter is ever saved to our servers — validation runs entirely on your device.
Validation Workspace
Validate UTR / NINO
Enterprise checks for United Kingdom tax identification numbers.
Instant one-by-one format validation
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 C1234567890
Invalid examples
- AB 12 34 56 (Missing suffix)
- 123456789 (Too short)
What this validator checks
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 known United Kingdom structure, including length, separators, letters, and checksum rules where public guidance includes them.
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
Related TIN validators
Get started today
Ready to validate at scale?
Start with 1,000 free validations per month, or talk to us about enterprise volume and custom integrations.
No credit card required · Cancel anytime