Self-Assessment
The system by which taxpayers calculate and report their own tax liability to HMRC and file annual returns. Applies to the self-employed, company directors, and those with complex affairs.
Independent editorial summary — not the official statute text. Read the official version on legislation.gov.uk.
Self Assessment is HMRC's system for collecting Income Tax from people and businesses whose tax is not already collected automatically. Tax is usually deducted automatically from wages and pensions, but people and businesses with other income must report it themselves in a Self Assessment tax return, filed after the end of the tax year to which it applies.
Anyone sending a return for the first time, or who registered before but did not need to send one for the previous tax year, must tell HMRC by 5 October and can be fined for failing to do so. HMRC calculates the tax owed based on what is reported, and the resulting bill must be paid by 31 January; how much tax is due depends on the taxpayer's Income Tax band, with a different rate applying to Capital Gains Tax if that is also owed.
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Official sources
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