HM Revenue & Customs announced on 9 September 2026 an improved online Self Assessment registration service. People filing for the first time for the 2025 to 2026 tax year must register by 5 October 2026 or risk a penalty, while the deadline for submitting the return and paying any tax owed is 31 January 2027.

HMRC said the streamlined process, available through a Personal Tax Account, includes pre-populated forms, save-and-return functions and confirmation by email or text. Those using it would receive a Unique Taxpayer Reference in their online account within 72 hours, rather than waiting up to 15 days for post. HMRC reported that more than 640,000 customers registered in the 12 months to 31 March 2026. Agents must continue using existing processes, including forms CWF1 or SA1.

Chief Customer Officer Myrtle Lloyd said anyone new to Self Assessment may not realise they need to register before submitting a return. HMRC also reminded customers who no longer need to complete a return to notify it as soon as possible. The department said around 300,000 customers would now have Child Benefit information pre-populated on their online returns for the High Income Child Benefit Charge.