Company DeadlineCalculator
Independent tool

HMRC Company Tax Return filing

CT600 filing deadline calculator.

Use this tool only for the Company Tax Return filing date. A CT600 is usually due 12 months after its Corporation Tax accounting period ends; the tax payment deadline is separate.

01

Your tax accounting period

A Corporation Tax accounting period cannot be longer than 12 months. A first set of accounts can therefore require two returns and two payment dates.

How this filing date works

Calculate when the CT600 return must be filed.

Use this page when you need the Company Tax Return filing date, not the Corporation Tax payment date. Even where a company has no tax to pay, it may still need to send a return when HMRC issues a notice to deliver one.

01
Confirm the tax accounting period

It is often the financial year, but it can differ in the first year or after a change to the year end.

02
Add 12 months for the normal CT600 filing date

The Company Tax Return is normally due 12 months after the end of the period it covers.

03
Keep payment and filing separate

Corporation Tax is normally paid earlier. Use the payment calculator if that is the date you need.

Need the payment date, not the filing date? Use the Corporation Tax payment calculator.

Common questions

CT600 filing deadline FAQ

The Company Tax Return, often called the CT600, is normally due 12 months after the end of the Corporation Tax accounting period it covers.

No. The filing date is normally 12 months after the accounting period ends. Corporation Tax payment is normally due earlier, after 9 months and 1 day for companies using normal payment timing.

Yes, if HMRC issues a notice to deliver a Company Tax Return, you must file it even if there is no Corporation Tax to pay.

Yes. A Corporation Tax accounting period cannot exceed 12 months, so a longer first accounts period can be split across two Company Tax Returns.

HMRC can charge late filing penalties even where no Corporation Tax is due. The initial penalty is generally triggered once the filing deadline is missed.

Keep the full picture

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