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What is a CT600 Return?

A CT600 is the UK Company Corporation Tax return which companies need to file with HMRC following end of the Companies accounting period

What is a CT600 Return?




A CT600 return is the name of the filing that UK companies must submit to HMRC after the end of their accounting period. Currently this is stipulated to be no later than 12 months after the end of the company's Accounting period, with any Corporation Tax payable due after 9 months and a day following the accounting period end.

The CT600 return is required to be filed digitally with HMRC, with the original CT600 paper form now obsolete being used only for the compilers reference. Along with the CT600 return HMRC also require that the Company accounts are also provided in a format known as IXBRL, where key information is tagged so that the document can be both machine read and viewed as a normal document. Unlike the CT600 the accompanying Company accounts can cover accounting periods greater than 12 months.

What information does a CT600 cover?

The CT600 return is divided into sections which relate to the different activities of the company.
The main sections are:

  • Company & Return Information - Name, Company Type UTR and Accounting Period.
  • Tax Calculation - Turnover, Income, Expenses, Reliefs, Losses, profits and Tax Payable.
  • Declaration - Accounts that are being submitted with return and the name of the person legally declaring/making the return.

Other sections include:

  • Capital Allowances - (e.g capital items purchased that have a lifespan greater than a year)
  • Enhanced Expenditure - Creative and Research & Development
  • Losses and Deficits
  • Other non-trading income (e.g Bank interest)
  • Disallowable expenses - (e.g advertising costs, entertainment)
  • Income from property - also includes property Capital expenses which are treated differently to above
  • Payments and repayments - Bank details to where refunds should be paid

Along with the main CT600 return there are also supplementary sections which we won't go into here. The most common is the CT600A for declaring Loans to company officers, but also there are supplementary sections for Tonnage (Boats) and other items that are normally related to Large of medium enterprises.

How is a CT600 return filed with HMRC?

The CT600 EasyDigitalFiling service enables you to fill in the sections that a company needs to report on, calculate tax and file directly with the HMRC gateway. To do this you must already have a HMRC CT600 Gateway Filing Account. The return must also include the IXBRL tagged accounts which are generated automatically if an associated Company accounts Filing has been added.

A simple company that has a very basic set of returnable items may in some cases be bale to use the HMRC CATO (Company Accounts and Tax Online) system to make the digital filing. However due to the narrow set of circumstances that the CATO system provides for most companies will need to file using another service (e.g EasyDigitalFiling).

Examples of companies that have to File using a service like EasyDigitalFiling are:

  • Small Sized companies - (£632K or greater in Turnover)
  • Extended Accounting period - Where its greater than 12 months
  • Most entities with property - Where Turnover is greater than £5,200 or a loss has been made
  • Foreign currency transactions
  • Adjustments for something reported in a previous years
  • Chargeable gains or losses
  • Financial instruments - e.g shares held
  • Non-trading income (except interest received)
  • Research and development costs
  • Complex loan-relationship entries
  • Capital allowances

This article is information only and has been prepared for general guidance on matters of interest only, and does not constitute legal, accounting, tax, investment or other professional advice or services. You should not act upon the information contained in this article without obtaining specific professional or legal advice. No representation or warranty (express or implied) is given as to the accuracy or completeness of the information contained in this article, and, to the extent permitted by law, Comdal Limited, its members, employees and agents do not accept or assume any liability, responsibility or duty of care for any consequences of you or anyone else acting, or refraining to act, in reliance on the information contained in this publication or for any decision based on it.