Company started trading part-way through its accounts year: Companies House accounts and CT600 figures
Short version. Keep the full Companies House accounts period when a company starts trading part-way through the year. If the Corporation Tax period starts later, enter its dates and appropriate tax figures separately from the statutory P&L.
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1. Establish the two periods
Accounts dates and Corporation Tax dates serve different purposes. Starting to trade can begin a Corporation Tax accounting period, but other events can also bring a company within the charge. Check the HMRC notice and business tax account. Do not assume incorporation or the first sale is always the correct tax start.
Fictional Cedar Example Ltd prepares accounts from 1 April 2024 to 31 March 2025. Its confirmed tax period is 1 October 2024 to 31 March 2025. The statutory accounts include the full year’s figures. The CT600 and computation cover the later period. HMRC receives the full accounts with box 85.
Qualifying pre-trading expenditure has its own tax treatment. Do not claim an expense again as a separate deduction if it is already included in the return’s deductible expenses. Choose the appropriate treatment from your prepared figures.
2. Enter and review the figures
On the supported ordinary route, separate figures allows either HMRC CT600 or Companies House & HMRC CT600. Enter full accounts figures on the Companies House accounts tab and period figures on each CT600 tab. Two returns are supported if the coverage exceeds 12 months. First CT600 ends sets their boundary within the existing date rules.
The enter-once route with divergent dates remains HMRC only and keeps its existing figure basis. Filed-elsewhere and remaining-only filings keep their existing scope. See the separate figures guide and dormant then trading.