How to Change Your Company Year End Date

You change your company's year end by telling Companies House the new date, online or on form AA01, before the filing deadline for the accounts you are changing. It is free, and you can shorten the year whenever you like, but you can normally only lengthen it once every five years and never beyond 18 months. The change also moves your filing deadline and usually your Corporation Tax dates, so it is worth planning before you click submit.

Key takeaways

• The year end is officially called the accounting reference date, or ARD.
• You can change it for the current financial year or the one immediately before it.
• Shortening: as often as you like, by a minimum of 1 day.
• Lengthening: to a maximum of 18 months, and normally only once every 5 years.
• You cannot change the date once the accounts for that period are overdue.

What is the accounting reference date?

The accounting reference date (ARD) is the day your company's financial year ends each year. Companies House sets it automatically when the company is formed, as the last day of the month in which the company's first anniversary falls. A company incorporated on 11 May gets an ARD of 31 May. Your annual accounts are made up to that date and a private company normally has 9 months from it to file them.

Nobody chose that date for a business reason. It is simply an accident of when the paperwork went in, which is why many directors later want to move it.

Why companies change their year end

• To line up with the tax year or VAT quarters, so that bookkeeping, VAT and accounts all close on the same date.
• To avoid a busy season. A retailer may not want a 31 December year end, when stock counts are hardest.
• To match another group company, so that parent and subsidiary report to the same date.
• To tidy up the first year, for example moving from an odd month end to 31 March.

Changing the date purely to buy filing time is a poor reason. It solves nothing if the records behind the accounts are still not ready.

The rules in brief

The rules are set out on the GOV.UK page change your company's year end. You can only change the current financial year or the one immediately before it, and only while the accounts for that period are not yet overdue.

The five year limit on lengthening does not apply if the company is in administration, if you are aligning dates with a subsidiary or parent company, or if Companies House has given special permission.

What happens to your filing deadline

A new year end means a new deadline for filing accounts. If you shorten the year, the deadline comes forward, sometimes to a date only weeks away, and Companies House will confirm it when the change is accepted. If you had been given an extension for that year, it falls away. If the new deadline has already passed when you make the change, you will have to pay a late filing penalty. Our guide to company accounts late filing penalties explains how those work.

First accounts are a special case. They are normally due 21 months after the date of incorporation, and lengthening the first financial year does not move that deadline. The general timetable is on GOV.UK under accounts and tax returns for private limited companies, and in our guide to company accounts deadlines.

The knock-on effect on Corporation Tax

Companies House and HMRC are separate. Changing your ARD does not automatically tell HMRC, and GOV.UK says you must update your accounting period dates with HMRC if you have shortened or lengthened your financial year.

A Corporation Tax accounting period cannot be longer than 12 months. If your accounts now cover, say, 16 months, you need two Company Tax Returns: one for the first 12 months and one for the remaining 4. Each has its own payment date, 9 months and 1 day after the period ends, and each return is due 12 months after the period ends. The details are in the GOV.UK guide to accounting periods for Corporation Tax, and our article on the Corporation Tax payment deadline shows how to count the dates.

Step by step: changing the date

1. Check your current ARD and filing deadline on the Companies House register.
2. Confirm the accounts are not overdue. If they are, file them first.
3. Decide whether to shorten or lengthen and check you are within the 18 month and 5 year limits.
4. Work out the new deadlines for accounts, Corporation Tax payment and the Company Tax Return before you commit.
5. Apply to Companies House online, or by post using form AA01. There is no fee either way.
6. Check the register shows the new date and the new accounts deadline.
7. Update your accounting period with HMRC. If you lengthened the year, do this before the original filing date of your Company Tax Return.
8. Change the year end in your bookkeeping software, and tell your bank or lenders if they expect accounts by a set date.

Worked example (illustrative)

"Harrow Lane Design Ltd", an illustrative example, has a 30 September year end. Its director wants 31 March instead, to sit alongside the VAT quarters. In October 2026 the accounts for the year to 30 September 2026 are not yet due, so that period can still be changed.

Option one is to shorten it to 31 March 2026, giving a six month period. That works, but the filing deadline is brought forward sharply and the books for those six months would need finishing almost at once.

Option two is to lengthen it to 31 March 2027, giving an 18 month period from 1 October 2025, which is exactly the maximum. The accounts would then normally be due by 31 December 2027. For Corporation Tax there would be two periods: 12 months to 30 September 2026, with tax payable by 1 July 2027, and 6 months to 31 March 2027, with tax payable by 1 January 2028. The company could not lengthen again for five years, but it could still shorten.

The director chooses option two and updates HMRC straight away. The company and dates are invented for illustration and are not a real client.

Common mistakes

• Leaving it until the accounts are overdue. By then the date is locked.
• Shortening by a day to gain time. The change can bring the deadline forward, not push it back.
• Forgetting HMRC. Companies House does not pass the change on for you.
• Missing the second tax return after a period longer than 12 months.
• Using up the five year allowance carelessly, then needing to lengthen again a year later.
• Overlooking other dates, such as VAT quarters, payroll year end and dividend planning, which do not move with the ARD.

How we can help

We check whether a change is allowed, map out the new deadlines, file the change with Companies House, update HMRC and prepare the accounts and tax returns for the new period. Company accounts start from £350 per year on a fixed fee. If your company is new, our guide to the first year of a limited company is a useful companion. See our company accounts service, view our pricing, or contact us well before your current filing deadline.