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HMRC internal manual

Company Taxation Manual

CTSA: the filing obligation: computations

Form CT600/CT200 includes a computation of the amount of tax chargeable.

The notice to deliver (CT603/CT203) also requires the company to provide ‘computations showing how entries on the return have been calculated from relevant figures in the accounts’. The computations can be in whatever format the company finds most appropriate for its business, but they must be sufficient to link the accounts with entries on the return.

Computations may include a detailed trading and profit and loss account along with any other analyses and explanations required for that purpose.

FA98/SCH18/PARA7 requires for CTSA accounting periods (ending on or after 1 July 1999) that companies must also include in the return an SA of the amount of tax payable for the period for which it is making the return, see CTM93110.

It must make the SA on the basis of the information in the return and after taking into account any reliefs or allowances:

  • claimed in the return,


  • required to be given for the accounting period.

You must regard a company tax return received as a return for an accounting period, even if it is not an accounting period, if:

  • the period is treated as an accounting period in the return,


  • the period is not longer than twelve months.