If you need to file a self-assessment tax return, a UTR is required. The Unique Taxpayer Reference has 10 digits and is provided by HMRC on registration for self-assessment. HMRC expect you to register within 3 month of commencing self-employment. You can fill out a UTR Request form (SA1) using the following link to SimpleTax's Self-Assessment Checklist.  We will send the form to your e-mail in pdf format which should be printed out and posted to HMRC. A UTR is usually sent within 6-8 weeks. Sign and post your UTR registration to: Central Agent Authorisation Team, National Insurance Contributions Office, Benton Park View, Newcastle upon Tyne, NE98 1ZZ To complete the SA1 registration form, you will need your National Insurance Number (NINO). The UTR can take a while to come through so apply a couple of months in advance so you can meet the filing deadline of 31 January. Keep the UTR number safe as you will need it whenever you contact HMRC. Business partnerships need a UTR for the firm and a UTR for each partner in order to file online.   Other Keywords: code; UTRno; working; U.T.R.; UTI