Companies House Edition AA01 Version 7.0 (03/26) 3 pages

Form AA01 — Change of accounting reference date

The Companies House paper form a company uses to move its financial year end by shortening or extending its current or previous accounting period.

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AA01 Change of accounting reference date · Change of accounting reference date
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What is AA01 Change of accounting reference date?

Every UK company has an accounting reference date: the day and month its financial year ends and its accounts are made up to. Form AA01 tells Companies House you are changing it, under section 392 of the Companies Act 2006, by shortening or extending either the current accounting period or the immediately previous one.

Companies House asks you to use its online service where you can, because paper forms take longer to process. The AA01 is the paper route, and an overseas company with a UK establishment must post the paper form. The form can't be used to change a period whose accounts are already overdue, or to extend a period beyond 18 months unless the company is in administration.

FileIt walks you through the five sections, pads the company number into its eight boxes, splits the date into the day, month and year boxes, and prints everything into Companies House's own AA01 PDF. The finished form is signed on behalf of the company. FileIt never files it for you.

Who fills it
A company changing its financial year end, usually through a director, secretary or its accountant
Law
Section 392 of the Companies Act 2006
Length
3 pages: 5 sections, then optional presenter details and a checklist
Signatures
One signature on behalf of the company on page 2 (there is no date box)
Edition
AA01 Version 7.0 (03/26)
Other ways
Online through Companies House's WebFiling service

Who needs to fill out AA01 Change of accounting reference date?

  • A private or public limited company that wants its financial year to end on a different date, for example to line up with its tax year, its trading cycle or a parent company.
  • An overseas company with a UK establishment changing its accounting reference date. Companies House says it must send the paper form by post.
  • An accountant or company secretary filing the change for a client company.
  • Not for limited liability partnerships. They use a separate form, LL AA01.

When to use AA01 Change of accounting reference date

  • When you want the current accounting period (the one that hasn't ended yet) to end earlier or later.
  • When you want to change the immediately previous period. Companies House must receive the form within the time allowed for delivering that period's accounts.
  • Before the accounts for the period are overdue. You can't change a period once its accounts are late.

What you need before you start

  • The company number and the company name exactly as on the Companies House register.
  • The date the period you're changing currently ends.
  • The new end date, and whether that shortens or extends the period.
  • If you're extending and have already extended in the last five years: which exception applies (administration, Secretary of State approval, aligning with a UK parent or subsidiary, or an overseas company). With Secretary of State approval, a copy of it.
  • Optionally, presenter contact details so Companies House can reach you about a query.

What’s on AA01 Change of accounting reference date

The 2026 edition has 3 pages. FileIt asks for it in 7 parts, and it is signed by Company (signed by a director or officer):

  1. Section 1: Company detailsCompany (signed by a director or officer)
  2. Section 2: The accounting period you are changingCompany (signed by a director or officer)
  3. Section 3: New accounting reference dateCompany (signed by a director or officer)
  4. Section 4: Extending more than once in five yearsCompany (signed by a director or officer)
  5. Section 5: SignatureCompany (signed by a director or officer)
  6. Presenter information (optional)Presenter
  7. Checklist (optional)Presenter

How to fill out AA01 Change of accounting reference date, step by step

1 Section 1: Company details

The 8-character company number (for example 01234567 or SC123456) and the full company name, as registered.

2 Section 2: Date of accounting reference period

The end date of the current, or immediately previous, accounting period: the period you are changing.

3 Section 3: New accounting reference date

Choose whether the period is being shortened or extended, then enter the new end date in the matching row. A shortened period ends earlier. An extended period ends later, but can't run beyond 18 months unless the company is in administration.

4 Section 4: Extending more than once in five years

Only if you're extending. If you have extended more than once in five years, tick the one category that lets you: the company is in administration, you have specific approval from the Secretary of State (enclose a copy), you're aligning with a parent or subsidiary undertaking established in the UK, or you're filing for an overseas company. If not, go to section 5.

5 Section 5: Signature

Signed on behalf of the company by a director, secretary, person authorised, permanent representative of an overseas company, administrator, receiver or another officer listed on the form.

6 Presenter information and checklist

Optional contact details for queries. They appear on the public record. Then work through the checklist on page 3.

Common mistakes to avoid

  • A company name or number that doesn't match the register exactly.
  • Entering the new date in the Shortened row when the period is being extended, or the other way round.
  • Trying to change a period whose accounts are already overdue.
  • Extending a period beyond 18 months when the company isn't in administration.
  • Extending more than once in five years without ticking an exception, or without enclosing the Secretary of State's approval.
  • Forgetting to sign the form.

After you fill it out

Print the AA01 from FileIt and have it signed on behalf of the company, or send it for signature with FileIt's eSignature.

Post it to the correct Companies House office for the company, listed at gov.uk/companies-house/offices. Companies House says it may return forms completed incorrectly or with information missing.

Companies House no longer posts a letter confirming the change. Search for the company on the Find and update company information service to check the new accounting reference date.

Keep a copy in the company's folder in FileIt, and diary the new filing deadline for the accounts.

Fill out AA01 Change of accounting reference date online with FileIt

  1. Pick the person. Choose someone from People and FileIt fills in their name, date of birth, address and other details it already knows.
  2. Answer plain-language questions. One part of the form at a time, with the official help text beside each question — 31 fields in all. Your answers save as you go.
  3. Check the live preview. Watch your answers land on the real Companies House form, and let FileIt do any worksheet arithmetic.
  4. Generate the official PDF. FileIt prints your answers into the agency’s own PDF and files it in that person’s folder in your vault. Sign it, or send it for e-signature.

FileIt fills the form — it never files or submits anything for you. Deliver the finished form to whoever asked for it, the way the form’s instructions say.

Start AA01 Change of accounting reference date now — it’s free

AA01 Change of accounting reference date: frequently asked questions

What is an accounting reference date?

The day and month a company's financial year ends each year. Its accounts are made up to that date.

Can I change the year end online instead?

Yes. Companies House has an online service and asks people to use it where they can, because paper forms take longer to process.

Are there limits on extending a period?

The form's limits are on extending: a period can't be extended beyond 18 months unless the company is in administration, and you may not extend more than once in five years unless one of the listed exceptions applies.

Can I change a period whose accounts are late?

No. The form says you can't change a period for which the accounts are already overdue.

Which period can I change?

The current accounting period, or the immediately previous one. For the previous period, Companies House must receive the form within the time allowed for delivering its accounts.

Who can sign the AA01?

A director, secretary, person authorised under section 270 or 274 of the Companies Act 2006, permanent representative of an overseas company, administrator, administrative receiver, receiver, receiver manager, Charity Commission receiver and manager, CIC manager or judicial factor.

Will I get a letter confirming the new date?

No. Companies House has stopped sending paper confirmation letters. Check the new date by searching for the company on its Find and update company information service.

Official sources

FileIt is not affiliated with or endorsed by Companies House or any government. This page explains the form in general terms and is not legal, tax or immigration advice. Always read the official instructions, and check that you are using the edition the recipient accepts. Page last reviewed 2026-09-28.

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