How do I claim a CIS refund as a self-employed subcontractor?

How do I claim a CIS refund as a self-employed subcontractor? You claim over-deducted CIS back through your Self Assessment tax return once the tax year ends on 5 April. There is no refund during the year while you are trading. For 2026-27, you can file from 6 April 2027. Not while you are still trading as a sole trader. Over-deducted CIS is claimed back through your tax return after the tax year ends on 5 April. If you stop trading, form CIS40 may let you claim that year's deductions early. On the self-employment pages. On the 2025-26 paper forms that is box 38 of the short pages (SA103S) or box 81 of the full pages (SA103F). Your gross pay before deductions goes in as your turnover. Yes, keep them. GOV.UK says HMRC may ask for evidence of your deductions. If you lose a statement, ask the contractor for a copy, or write to HMRC if you cannot get one. Read the full answer, with every source, at rightotax.co.uk.