HMRC Company Tax Returns (CT600) – All you need to know!

This blog is aimed to give insights on HMRC Company tax return, its requirements, deadline, and penalty charges.

A company tax return, also called CT600 form, is filed by companies to report their spending, corporation tax figures, and profits to HMRC. A company must file a CT600 form every year, and the due date will be the respective company’s accounting period.

For instance,

HMRC Company Tax Returns (CT600)

Scenario 1: If you started business on 15th January 2020, your financial year end would be 31st January 2021. This denotes that you must file two tax returns in the first year, i.e., for the first 17 days and another for the following 12 months.

Scenario 2: If your business starting date is April 1 2020, you must deliver the Company Tax return no later than a year after the end of the accounting period.

A company tax return must show,

  • Your company’s corporation tax bill and
  • Profit or loss for corporation tax

Before you file a company tax return, you will need to have

  • Taxable profit of your company
  • Government gateway credentials (User ID & Password)

What all required to fill in a CT600 form?

A complete CT600 form has more than 10 pages; however, you have to mention the necessary relevant details to your business. Some of the mandatory questions are Company’s information, accounting period, tax calculation, income, taxable profits, deductions, etc.

Once you submit your online return to HMRC, you will receive an acknowledgment. This also means that HMRC can amend the return to correct mistakes that are believed to be incorrect.

Paying corporation tax

Corporation Tax and related amounts should be paid online and the deadline for paying Corporation Tax is before filing Company Tax Return, and all the necessary figures in the form should be within single iXBRL computations file.

Are you new to Corporation Tax in the UK? Read to know more.


As part of the Company Tax Return, you must also include computations to show figures in the Company Tax Return form.

 What if you have missed filing CT600?

If you miss filing CT600, HMRC may charge you with penalties as mentioned below

One day late – £100

90days – Additional £100

Six months – HMRC estimates your corporation tax bill and adds 10% as a penalty.

One year – Additional 10% of tax liability

Note: If your tax return is delayed for consecutive three times, the £100 will become £500 each

At DataTracks, we collaborate with over 10,000 UK firms, providing iXBRL tagging services to ensure timely submission of their final accounts and company tax returns to Companies House and HMRC. Specializing in the conversion of accounts to iXBRL format, we streamline the filing process with precision and expertise. For more information on our iXBRL services, reach out to us at