A UTR (unique taxpayer reference) number is a 10-digit number completely unique to each and every UK taxpayer. Whether the taxpayer is to register for self-employment or is an individual or part of a partnership or company, a UTR number is needed to file a Self Assessment tax return online or via post.
The most important reason why you need a UTR number is for completing self-assessment tax returns – but there are other reasons too.
UTR numbers are necessary for CIS (construction industry scheme) tax refund registration.
They are also important when working with accountants or other financial advisors.
Without a valid UTR number, your self-assessment tax return won’t be submitted correctly and this can result in a potential fine.
Furthermore, if you are self-employed and have not notified HMRC – and have therefore not received a UTR number – this too can be dangerous. If HMRC finds out, you may have to pay a hefty fine and potentially face criminal prosecution.