Financial year, tax year and company year end

The years side by side

So "financial year" can mean two things: your company's own year, or the 1 April to 31 March year that Corporation Tax rates are set for. If someone mentions the financial year, it may be worth checking which one they mean.

How a company's year end is set

Companies House says a new company's first year end is the last day of the month in which the first anniversary of its set-up falls. After that, it falls on the same date each year.² So a company set up on 10 March has its first year end on 31 March the following year.

Companies House also says a company can make up its accounts to its accounting reference date or to a date up to 7 days either side of it.²

A company can change its year end, also known as its accounting reference date. GOV.UK says it can shorten its financial year as often as it likes, and lengthen it to a maximum of 18 months, but normally only once every 5 years. It cannot change its year end when its accounts are overdue.⁴ If you change it, GOV.UK says you must also update your accounting period dates with HMRC.⁴ Companies House says that from 1 April 2028 a company will need to give a business reason to shorten its accounting reference period more than once in 5 years, and that this change is subject to regulations still to come.²

How to find your company's year end

• On Companies House. Search for your company on the Companies House register. Its overview page shows "Next accounts made up to" with a date and "due by" with the filing deadline for those accounts. The "made up to" date is the end of the next financial year whose accounts are due, so the day and month show your year end.⁷
• With HMRC. GOV.UK says to sign in to your business tax account to check the dates of your Corporation Tax accounting period.³

If the two do not line up, for example after a year end was changed, ask your accountant which dates HMRC has on record.

Which deadlines follow from which year

• Company accounts: a private company files them at Companies House 9 months after the end of its financial year (first accounts have their own deadline).⁵
• Corporation Tax: payment is due 9 months and 1 day after the end of the accounting period, and the Company Tax Return 12 months after it.⁵
• Self Assessment: you fill in the return after the end of the tax year it covers. The online return and the payment are due by 31 January after the tax year ends.¹

Corporation Tax rates are set for years that start on 1 April. If a company's accounting period covers two of those years and the rates differ, GOV.UK says to work out how many days each rate applied and the tax due for each.⁶

If you are a sole trader

A sole trader has no company year end, but may still prepare accounts to a date of their choice. GOV.UK says that if you prepare accounts you choose the dates you keep records to and from, usually the same dates each year, and that it may be easier to complete your tax return if the dates match the tax year (6 April to 5 April), because HMRC works out tax based on the tax year. If you do not prepare accounts, GOV.UK says you record your income and expenses for each tax year.⁸

Example: a company with a 31 December year end

This is an example to show how the dates fit together, not a real company. It assumes the company is past its first year and has not changed its year end.

Example dates for a financial year 1 January to 31 December 2025

What	Example date
Company financial year and Corporation Tax accounting period	1 January 2025 to 31 December 2025
Accounts due at Companies House	30 September 2026
Corporation Tax payment due	1 October 2026
Company Tax Return due	31 December 2026
A director's tax year that overlaps most of this company year	6 April 2025 to 5 April 2026
If that director sends a Self Assessment return: online return and payment due	31 January 2027

We worked these dates out from the rules above; they are not copied from a GOV.UK example. Companies House counts the 9 months to the last day of the month when the year end is the last day of a month, which is why the accounts date is 30 September.² The financial year in this example covers two Corporation Tax years: 1 January to 31 March 2025 falls in the year starting 1 April 2024, and the rest in the year starting 1 April 2025.⁶

Your own deadlines are on your company's Companies House record and in your HMRC business tax account. Check those rather than work them out from an example. See When are UK company accounts due?