Overview
- HMRC reports roughly 5.65 million returns were still outstanding at the start of January, with the online filing deadline on January 31.
- January 31 is also the payment date for the 2024–25 bill plus, where required, the first 2025–26 payment on account, which can create large immediate demands.
- Late filing brings an initial £100 penalty, and unpaid tax accrues interest at Bank Rate plus 4%, currently about 7.75%, until cleared.
- Share capital gains now face higher rates of 18% for basic-rate and 24% for higher and additional-rate taxpayers after the October 2024 Budget, and HMRC warns some returns may miscalculate these liabilities.
- Help is available from Tax Help for Older People, TaxAid and HMRC webchat, while Martin Lewis urges early filing and nearly 340,000 Self Assessment payments have been made via the HMRC app since April 6, 2025.