Can I claim back CIS deductions from previous years?

Can I claim back CIS deductions from previous years? Usually yes, for up to 4 years after each tax year ends. As at 16 October 2026, the oldest year you can normally still claim is 2022-23, and that return must reach HMRC by 5 April 2027. Usually 4 years from the end of the tax year. In October 2026 the oldest year you can normally still claim is 2022-23, which ended on 5 April 2023, and the return for it must reach HMRC by 5 April 2027. Normally not. The usual 4-year limit for 2021-22 ended on 5 April 2026. The law gives extra time in two cases: if HMRC sent you a notice to file within the 4 years, or if HMRC has issued a determination for that year. You can amend a return within 12 months of the filing deadline. After that, you write to HMRC to claim overpayment relief, which is also allowed up to 4 years after the end of the tax year. Read the full answer, with every source, at rightotax.co.uk.