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How do I file my Company Tax Return?

All limited companies must complete a company tax return (CT 600). The return must be sent to Her Majesty’s Revenue and Customs (HMRC) within the correct period of time.

Who needs to file a Company Tax Return?

All limited companies must complete a company tax return (CT 600). The return must be sent to HM Revenue and Customs (HMRC) within the correct period of time.

What does a Company Tax Return contain?

We will look at the key features of the CT600, which is produced automatically via online filing. A copy of the form can be downloaded below for reference.

Boxes that require completing Details/Action required
Company information Boxes 1 – 4  The basic company details.
About this return Boxes 30 – 35 The return must state the accounting period to which it relates. 
About this return Boxes 80 – 85 Tick the relevant box.
Tax calculation Box 145 Turnover – from the profit and loss account.
Income Boxes 155 – 190 Box 155 Adjusted profit from the corporation tax computation. Box 160 Trading losses brought forward and offset in this accounting period. Box 170 Income from non-trading loan relationships – bank interest. Box 190 Property income.
Chargeable gains Boxes 210 – 220 Chargeable gains.
Profits before deductions and reliefs Boxes 235 The amount on which corporation tax is payable. 
Tax calculation Box 440 The corporation tax due for period.

For more on using use HMRC’s free filing services click here.

How difficult is it to complete a Company Tax Return?

You can prepare and file your own company tax return. However, unless you feel completely confident in completing the return yourself, then it may be advisable to employ the services of an accountant.

When do I need to file a Company Tax Return?

There are different deadlines for filing the return and the payment of tax:

  1. The corporation tax return must be filed to HMRC within 12 months after the accounting period end to which it relates.
  2. Any corporation tax due must be paid electronically by nine months and a day after the accounting period end.

For example – a company with a year end 31 December 2023 must pay any corporation tax due by 1 October 2024 and file the return by 31 December 2024.

How can I file a Company Tax Return?

Companies must file their corporation tax return online with HMRC. The documents which must be submitted alongside the tax return, are the accounts and corporation tax computations.

Companies must register with HMRC to file online and obtain a user ID and password.

Companies may use the free software provided by HMRC to submit the tax return, or they may purchase software which is commercially available.

As of April 2024, HMRC have introduced an additional information form. For all claims for creative industry tax reliefs or creative industry expenditure credits, this must be submitted with the Company Tax Return. The form should be used for supporting evidence, on either the same day or the day before the Company Tax Return is submitted. 

Use our Corporation Tax Calculator to find out how much you will owe for the current tax year.

What are the penalties for filing late?

Late filing penalties from HMRC are:

  • less than three months late – £100
  • over three months late – £200
  • over 12 months late – 20% of the tax due.
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