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When managing your own business, there are a series of legal forms that require submission to HMRC. One of these will be your CT600, otherwise known as a company tax return.

What is a CT600 form?

Simply put, a CT600, otherwise referred to as a Company Tax Return, is the filing required to pay tax on your earnings. From small businesses to larger corporate firms, this tax payment is required and is referred to as corporation tax. The deadline for submitting your CT600 to HMRC is 12 months after the end of the accounting period covered by the return. This is very often the same as the financial year covered by your annual accounts but can vary if it your business’ first year of trading.

Do you need to file a CT600 form?

If you are due to file a company tax return, you should receive ‘Notice to Deliver a Company Tax Return’ correspondence in the post. If you receive this notice but have made a loss over the financial year, you are still required to file a CT600 even though you are not liable to pay any tax due to loss of earnings.

What does a CT600 cover?

A CT600 is partitioned into the various actions of your business, such as:

  • Company & Return data. Your business name and type, its UTR and accounting period.
  • Tax calculation. Your business’ turnover, profit & loss report, income and expenses.
  • The declaration. Your business’ account complete for submission, along with the name of the staff member legally making the return.

Within these segments will be the opportunities to inform HMRC of:

  • Your business’ capital gains
  • Your business’ expenditure
  • Non-trading income
  • Bank details for refunds and returns

How to submit a CT600

HMRC require all company tax returns to be digitally filed through HMRC’s gateway. You will need your gateway login details for this process.

What are the penalties for a late filing?

The penalties for a late filing of your CT600 vary depending on the period of time you have overrun.

If you miss the deadline by one day, you will be charged a total of £100.

If you overrun the deadline by three months, you will be charged a total of £200.

If you miss the deadline by six months, HMRC will estimate your Corporation Tax bill and add 10% as a penalty.

If you are 12 months late, HMRC will add another 10% of your tax liability, a 20% fine in total.

If you require any further information on your business’ CT600, or if you have any confusion with the information required within the documents, get in touch with a member of our knowledgeable Cain & Co team by calling us on 020 8087 1341 or emailing us at and we will be happy to assist you.