Why companies change it

To line up with the tax year or a seasonal business, to match a parent or subsidiary, or to give a first year a sensible shape. The Corporation Tax side follows the accounts: an accounting period for Corporation Tax can’t be longer than 12 months, so a long period of accounts means two Company Tax Returns3. Think that through before extending, and update the dates with HMRC too3.

Shortening

You can shorten the current or the previous period “as often as you like, and by as many months as you like” for now2. Shortening brings the accounts deadline forward, but never to less than three months from when Companies House receives the change. The new deadline is the longer of2:

  • 9 months from the new year end (for a private company); or
  • 3 months from the date Companies House receives the notice.

From 1 April 2028, Companies House says you’ll need to give a business reason to shorten more than once in five years2.

Extending

A period can’t be extended so that it lasts more than 18 months from its start date, unless the company is in administration1,2. Don’t simply add six months to the current year end: if the period is already longer than 12 months (a first year often is), that can take it past 18 months and the change is rejected2.

You also can’t extend again within five years of the end of a period you previously extended1. The exceptions are1:

  • the new date lines up with a UK parent or subsidiary undertaking’s;
  • the company is in administration; or
  • the Secretary of State directs that the rule doesn’t apply.

Check your company’s dates and set a reminder

Search the Companies House register. Your company page shows its filing dates, what to file next and a reminder you can set.

When it’s too late

A change to the previous period can’t be made once its accounts filing deadline has passed1. In Companies House’s words, “If your accounts are overdue, it is too late to change your ARD”2. Changing the year end is not a way out of a missed deadline: if you need more time to file, read can you get more time to file company accounts? instead.

After the change

Companies House no longer sends a letter to confirm a new accounting reference date: check the company’s page on the register to see it2. Your next accounts and Company Tax Return deadlines move with it. To see the knock-on dates, use the deadline checker with the new year end, or read company accounts and tax filing deadlines.

Filing the change

Fileyear’s year end change checks the 18-month and five-year rules and whether the period is already overdue, shows your new accounts and tax deadlines, and files form AA01.