What is CT600?

CT600 is part of a tax return form used by companies to submit their accounting records to HMRC.

There are a number of supplementary pages that are included with the CT600 to complete a company tax return.

The tax office will only accept the submission of a CT600 online and after the CT603 is filed. A paper copy of a CT600 is only acceptable if it is an amendment to the online original.

A company tax return is not necessary if your business is classed as a sole trader or partnership in which case you will complete a self assessment tax return.

Who has to complete a CT600?

Registered companies in the UK and any foreign companies with a UK office or branch will be sent a notice to deliver a company tax return by HMRC.

The responsibility to complete the company tax return on time and pay any corporation tax bill lies with the company director.

Some trading but unincorporated organisations may have to complete a company tax return. For example housing associations, members clubs and trade associations.

CT600 corporation tax computation

The figures included in a CT600 are used to produce the amount of corporation tax a company owes HMRC.

The rate of corporation tax is 19% for most companies which means the company will pay 19% of their profits in corporation tax unless previous losses have been made.

From April 2023 the corporation tax rate increases for companies with taxable profits of over £50,000 with the maximum corporation tax rate for limited companies set at 25%.

Your corporation tax bill must be paid electronically usually within nine months and one day after the end of the accounting period. The tax office let you pay your corporation tax early if you wish.

When is the CT600 submission deadline?

Your CT600 company tax return normally has to be submitted no later than 12 months after the end of your accounting period or three months from when a notice CT603 is received.

The filing dates are legal requirements and HMRC will impose late penalties for company tax returns that are submitted late.

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