Register for Self Assessment: the right route.

Which registration route applies?

First use the Self Assessment filing checker. If a return is needed, the registration service asks why and whether you sent a return last year. The route differs for a sole trader, a partner and someone registering for other income.

If an old account is inactive, use the service to find out whether it must be reactivated. Obtaining a second UTR is not the way to reactivate an existing record. Check registration and reactivation.

What information is needed?

• Your identifying and contact details, including your National Insurance number where requested and your current address.
• An existing UTR if you already have one; check previous HMRC correspondence or your account.
• For a sole trader, the date self-employment started and a description of the work.
• For online registration, sign-in details; the service can require identity evidence such as a passport or driving licence.

Provide this information only on the linked HMRC service. AX Calculators has no registration form and does not request or store it. Read the first-time sole-trader route; find an existing UTR.

How long does a UTR take?

For the first-time sole-trader route checked here, online registration places the UTR in the Personal Tax Account within 72 hours. Postal registration usually takes 15 working days, or 21 working days if abroad; busy periods can take longer. Source: first-time sole-trader registration. Other routes can have different processing times.

Do not confuse a UTR with an activation code or a National Insurance number. If it has not arrived, use the response-time link within the registration guidance rather than submitting duplicate registration requests.

What happens after a missed deadline?

For 2025/26, registration was normally due by 5 October 2026. Register now if a return is needed. HMRC’s later notice can allow 3 months to file, but payment remains due by 31 January 2027. A failure-to-notify charge can arise if tax remains unpaid; it is not the same as the fixed late-filing charge. Read the filing rule; read the penalty distinction.