CT600 Explained: A Beginner's Guide to the Company Tax Return
A CT600 is a Company Tax Return sent to HMRC. It reports the company’s taxable profit and Corporation Tax calculation for an accounting period. It is separate from annual accounts filed with Companies House: most companies must deal with both organisations and their deadlines are different.
What does a Company Tax Return include?
The return normally includes the CT600 form, accounts and tax computations in the required digital format. The calculation starts with accounts profit but may then adjust for tax rules, such as disallowed expenses, capital allowances or reliefs. That is why a simple profit figure is not always the final taxable profit.
When is a CT600 due?
The usual filing deadline is 12 months after the end of the accounting period, but Corporation Tax payment is normally due earlier—9 months and 1 day after the period end. Build both dates into the company calendar.
Practical checklist
- Reconcile bank, sales, purchases, payroll and director-loan records.
- Prepare statutory accounts and tax computations.
- File the return using compatible software or an accountant.
- Keep records supporting the figures and payment.
Practical next steps
- Reconcile bank, sales, purchase and payroll records before preparing accounts.
- Prepare the tax computation from the accounts rather than guessing from bank balance.
- Use compatible filing software or a qualified accountant.
- Keep the filed return, computations and supporting records together.
