Corporation Tax accounting periods and financial years
How accounting-period amounts are split when rates or rules belong to different financial years.
How accounting-period amounts are split when rates or rules belong to different financial years.
Split a straddling accounting period by exact days
Reviewed · Current · Law · Current reviewed treatment; earlier start date not yet established
When an accounting period falls in more than one financial year, apportion profits and other amounts on a time basis and calculate each financial-year part separately.
A blended rate or one annualised band is not equivalent. Short-period limits are also reduced proportionately; strict calculation uses days.
Exceptions and branches
- A more specific statutory apportionment rule controls where one applies.
Related concepts
Linked from
Sources
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Corporation Tax Act 2009, section 8 — Section 8(1) to (4). Primary authority.
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Corporation Tax Act 2010, section 1172 — Section 1172. Primary authority.
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Corporation Tax Act 2010, Part 3A — Section 18D(4). Primary authority.
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CTM03930: short accounting periods — Strict calculation uses days. Official guidance.
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CTM03955: periods straddling 1 April 2023 — Strict-time split and worked example. Official guidance.
Knowledge version: sterling-knowledge@2026-09-11.7. Last checked 11 September 2026.