# AA01: changing a company’s accounting reference date

- **Canonical URL:** https://formspedia.com/uk/aa01/
- **Last updated:** 2026-11-05
- **Country & Language:** United Kingdom (`en-GB`)
- **Form:** AA01
- **Revision:** 03/26 Version 7.0
- **Issuing Agency:** Companies House
- **Tax Area:** Registration, representation and benefits
- **Who Must File:** A company (or an overseas company with a UK establishment) changing the accounting reference date of its current or immediately previous period; signed by a director, secretary, person authorised under s.270/274, permanent representative of an overseas company, administrator, receiver or other listed officeholder. LLPs use LL AA01.
- **Filing Method:** Online through Companies House WebFiling (authentication code) or filing software; paper AA01 by post to Companies House, Crown Way, Cardiff CF14 3UZ. Overseas companies with a UK establishment must post the paper form.
- **Filing Deadline:** Must be received within the period allowed for delivering the accounts for the current or immediately previous accounting reference period; no change once those accounts are overdue (GOV.UK AA01 page; CA 2006 s.392(4))
- **Legal Basis / Statute:** Companies Act 2006, section 392 (with sections 390, 391 and 442)
- **Official Form PDF:** https://assets.publishing.service.gov.uk/media/69f9dd2e097169e6a7a76ff4/AA01_V7.0-final.pdf

A company's accounting reference date is the day its financial year ends, and the accounts deadline at Companies House runs from it. AA01 is the notice under section 392 of the Companies Act 2006 that moves that date, either for the period the company is in now or for the one just before it. The PDF on GOV.UK is version 7.0, dated 03/26, and has three pages. Moving the date shortens or lengthens one period and then sets the date for every later year.

### Which period AA01 can change, and when it cannot be used

Section 392(1) lets a company give notice of a new accounting reference date for its current accounting reference period, or for the previous one, together with all later periods. The notes beside section 2 of the form explain the two terms: the current period is the one that has not yet ended, and the immediately previous period is the one right before it. A period two or more years back cannot be reopened with AA01.

Page 1 lists two uses the form does not cover. It cannot change a period whose accounts are already overdue, and it cannot stretch a period past 18 months unless the company is in administration. Section 392(4) puts the first bar in statutory terms: no notice for the previous period once the period for filing its accounts has expired.

A company does not need AA01 to close its books a few days off the reference date. Section 390 lets the directors end a financial year on the accounting reference date or on another date no more than seven days before or after it, and the Companies House accounts guidance repeats that 7-day margin.

For a new company, the first accounting reference date is the last day of the month in which the first anniversary of incorporation falls, and the same day and month then repeat every year (section 391(4)). A company incorporated on 15 March 2026, for example, starts with a reference date of 31 March 2027.

A limited liability partnership files LL AA01, a separate form with its own GOV.UK page (version 6.0). An overseas company with a UK establishment uses AA01 itself; the GOV.UK page for the form says it must send the paper version by post. Registering that establishment is covered in [OS IN01](/uk/os-in01/).

### Shortening and extending: the limits in section 392

Under section 392(2), a shortened period ends the first time the new date falls after the period began, and an extended period ends the second time it falls. Shortening has no limit on frequency or length at present; the Companies House accounts guidance says you can shorten as often as you like and by as many months as you like. The same guidance announces that from 1 April 2028 a business reason will be needed to shorten more than once in 5 years, and adds that this depends on forthcoming regulations.

Extending has two limits. An extended period may not exceed 18 months, and a notice that would take the current or previous period past 18 months is ineffective, except for a company in administration (section 392(5)). The second limit is the five-year rule in section 392(3): a notice extending a period has no effect if it is given less than five years after the end of an earlier period that was itself extended under section 392. Three exceptions in the Act lift that rule:

- the company is a subsidiary or parent undertaking of another UK undertaking and the new date matches that undertaking's date

- the company is in administration under Part 2 of the Insolvency Act 1986 or Part 3 of the Insolvency (Northern Ireland) Order 1989

- the Secretary of State directs that the rule does not apply

Section 4 of AA01 adds a fourth box for a form submitted on behalf of an overseas company. The Overseas Companies Regulations 2009, regulation 37, rewrite section 392 for overseas companies that do not have to prepare and disclose accounts under their parent law, and that version has no five-year rule; the 18-month limit and the overdue-accounts bar remain.

A first accounting reference period may be more than six months and up to 18 months long, starting on the day of incorporation (section 391(5)). The accounts guidance says no extra restrictions apply when the first date is changed, and that the day of incorporation counts as day one when the first period is stretched to 18 months. In the March 2026 example, moving the first date from 31 March 2027 to 31 August 2027 keeps the period under 18 months; 30 September 2027 would run past it.

### How to fill in AA01 section by section

Complete the form in typescript or in bold black capitals. The form treats every field as mandatory unless it is marked with an asterisk or described otherwise; no field has an asterisk, and the only conditional part is section 4, which its note limits to an extension caught by the five-year rule. The numbered frames in the image show sections 1 to 3 on page 1; sections 4 and 5 are on page 2.

| Section | What to enter | Where the entry comes from |
| --- | --- | --- |
| 1 | Company number in the eight boxes and the company name in full. | The company's entry on the public register, character for character. |
| 2 | "Accounting period ending on": the date the current or immediately previous period ends now, as dd mm yyyy. | The existing accounting reference date on the register, for the period you are changing. |
| 3 | One date only: either "Date shortened so as to end on" for an earlier end, or "Date extended so as to end on" for a later end. | The directors' decision on the new year end. The extended date must keep the period within 18 months. |
| 4 (page 2) | Answer Yes or No to the question on extending more than once in five years. On Yes, tick one box: administration, Secretary of State approval, alignment with a UK parent or subsidiary, or overseas company. | Earlier AA01 filings in the company's filing history. For the Secretary of State box, enclose a copy of the approval. |
| 5 (page 2) | Signature of the person signing on behalf of the company. | The signatory list printed under the signature box. |
| Presenter information (page 3) | Contact name, company name, address with postcode and country, DX and telephone. | Optional. Companies House uses it if there is a query on the form, and searchers of the register can see it. |

Section 2 is the date the period ends before the change, and section 3 is where it will end afterwards. A company with a 31 December reference date that wants its current period, which began on 1 January 2026, to end on 30 June 2027 enters 31 12 2026 in section 2 and 30 06 2027 in the extended box. That period runs to exactly 18 months, the most section 392(5) allows outside administration.

AA01 needs a real signature in section 5. The signatory list is a director, a secretary, a person authorised under section 270 or 274 of the Companies Act 2006, the permanent representative of an overseas company, an administrator, an administrative receiver, a receiver, a receiver manager, a Charity Commission receiver and manager, a CIC manager or a judicial factor. For a United Kingdom Societas, strike out "director" and give the organ of the UKS the signatory belongs to. Page 3 states that everything on the form goes on the public record.

### Deadline for AA01 and the new accounts due date

The GOV.UK page for AA01 says the notice must be received within the period allowed for laying and delivering the accounts for the current or the immediately previous accounting reference period. In the accounts guidance the same rule reads: change the date before the filing deadline of the accounts for the period you want to change. The date that counts is receipt, so a posted AA01 has to arrive in time, not merely be sent.

Moving the date also moves the accounts deadline. Outside a first period, a private company has 9 months and a public company 6 months from the end of the accounting reference period (section 442(2)). When a period is shortened, section 442(4) and section 5.3 of the accounts guidance give the later of two dates: the normal 9 or 6 months from the new reference date, or 3 months from the date Companies House receives the AA01.

Take a private company with a 30 June reference date whose previous period, 1 July 2025 to 30 June 2026, has accounts due by 31 March 2027. If an AA01 shortening that period to end on 31 March 2026 is received on 10 November 2026, the 9-month deadline would be 31 December 2026, but the 3-month alternative runs to 10 February 2027, so 10 February 2027 applies.

If the first period is longer than 12 months after the change, the first-accounts rule in section 442(3) applies instead: 21 months from incorporation for a private company, or 18 months for a public one, or 3 months after the reference date if that ends later. The GOV.UK year-end page says changing the date changes the filing deadline unless the first financial year is being lengthened. After filing, check the new date and deadline on the company's public record; Companies House stopped sending paper confirmation letters in March 2022.

### What makes an AA01 fail or lead to a penalty

The Companies House sources name these outcomes for AA01 itself:

- The accounts for the period are already overdue. GOV.UK says it is then too late to change the date, and page 1 of AA01 rules it out.

- Six months are added to the end of a period without counting from its start. The accounts guidance warns this can take the period past 18 months, and the application will be rejected.

- An extension is given less than five years after the end of an earlier extended period and none of the exceptions applies. Under section 392(3) the notice has no effect.

- An extension of the accounts filing deadline had been granted for the period being changed. That extension no longer applies once the date moves.

- The new filing deadline has already passed when the change is made. The guidance says the company then gets an automatic late filing penalty.

- The form arrives with information missing or completed incorrectly. Page 3 says Companies House may return it, and its checklist asks for matching company details, section 2 completed, the new date in section 3, section 4 where it applies, and a signature.

### Where to get AA01 and how to send it

The PDF is on the GOV.UK page [Change your company accounting reference date (AA01)](https://www.gov.uk/government/publications/change-your-company-accounting-reference-date-aa01), last updated 17 September 2026, next to a link to the online service. That page recommends filing online because paper forms sent by post take longer to process. The online route goes through Companies House WebFiling, which asks for the company authentication code, and GOV.UK says you may need to verify your identity with GOV.UK One Login first. Filing software is another route listed in the accounts guidance.

The form's page 3 points to the Companies House offices page for the postal address. That page sends documents for companies on every UK register to the main office:

Companies HouseCrown WayCardiffCF14 3UZDX 33050 Cardiff

The office page says post sent elsewhere may be redirected and take longer, and that delays in transit are not accepted as a reason to appeal a late filing penalty. Its advice when posting close to a deadline is to use a guaranteed delivery service, which matters for AA01 because the notice has to be received within the filing period.

### Questions about changing a year end

#### Does changing the year end at Companies House change the Corporation Tax accounting period?

The GOV.UK year-end page says it will normally affect the Corporation Tax accounting period, and that you must update the accounting period dates with HMRC after shortening or lengthening the financial year.

#### Is there a fee for filing AA01?

The Companies House fees page, last updated 25 September 2026, has no entry for a change of accounting reference date.

#### Can the year end move twice in a row?

Shortening can be repeated under the current rules. The accounts guidance says that from 1 April 2028 a business reason will be needed for more than one shortening in 5 years, subject to forthcoming regulations. A second extension within five years of the end of an earlier extended period only works if section 4 of AA01 applies to the company.

### Sources

- [Companies House AA01, change of accounting reference date, 03/26 version 7.0](https://assets.publishing.service.gov.uk/media/69f9dd2e097169e6a7a76ff4/AA01_V7.0-final.pdf)

- [Change your company accounting reference date (AA01), GOV.UK](https://www.gov.uk/government/publications/change-your-company-accounting-reference-date-aa01)

- [Preparing and filing Companies House accounts, GOV.UK](https://www.gov.uk/government/publications/filing-your-companies-house-accounts/life-of-a-company-part-1-accounts)

- [Change your company's year end, GOV.UK](https://www.gov.uk/change-your-companys-year-end)

- [Change your limited liability partnership accounting reference date (LL AA01), GOV.UK](https://www.gov.uk/government/publications/change-your-limited-liability-partnership-accounting-reference-date-ll-aa01)

- [Tell Companies House about changes to your limited company, GOV.UK](https://www.gov.uk/file-changes-to-a-company-with-companies-house)

- [Companies House office access and opening times, GOV.UK](https://www.gov.uk/government/organisations/companies-house/about/access-and-opening)

- [Companies House fees, GOV.UK](https://www.gov.uk/government/publications/companies-house-fees/companies-house-fees)

- [Companies Act 2006, section 390, legislation.gov.uk](https://www.legislation.gov.uk/ukpga/2006/46/section/390)

- [Companies Act 2006, section 391, legislation.gov.uk](https://www.legislation.gov.uk/ukpga/2006/46/section/391)

- [Companies Act 2006, section 392, legislation.gov.uk](https://www.legislation.gov.uk/ukpga/2006/46/section/392)

- [Companies Act 2006, section 442, legislation.gov.uk](https://www.legislation.gov.uk/ukpga/2006/46/section/442)

- [Overseas Companies Regulations 2009, regulation 37, legislation.gov.uk](https://www.legislation.gov.uk/uksi/2009/1801/regulation/37)