To get UTR number (i.e. Unique Taxpayer Reference) you need to register with HM Revenue & Customs (HMRC) for Self Assessment tax return.
Most people would get their UTR numbers after becoming self-employed.
To register as self-employed and for Self Assessment tax return (this gets you UTR number) follow the steps on HMRC website.
The letter with your UTR number would normally come in about 7-10 days to your address.
Please bear in mind that you would need to have your National Insurance number to register as self-employed and for Self Assessment tax return (this gets you UTR number).
If you feel this is too complicated for you, just ask your accountant (or find one) to do it for you.
