🇬🇧 HMRC Mathematical Validator
UTR Number Checker
Validate your 10-digit Unique Taxpayer Reference against the official HMRC Modulus 11 algorithm.
Awaiting Input...
Please enter all 10 digits.
Where to find your UTR
Previous Tax Returns or Self Assessment Statements
Inside your HM Revenue and Customs (HMRC) online account
Letters from HMRC ("Welcome to Self Assessment")
The official HMRC Mobile App
Why use Modulus 11?
A UTR is not just a random 10-digit sequence. The very first digit is a mathematical "check digit" calculated from the remaining 9 digits using a specific weighting algorithm. Our validator runs this exact mathematical check. If you make a typo, even if you enter 10 digits, the engine will detect the mathematical error instantly, preventing rejected payrolls and delayed tax filings.