A company’s accounting reference date (ARD) determines when its financial year normally ends. For UK companies registered with Companies House, getting this date right matters because it affects the company’s accounting periods, filing deadlines and the timing of annual accounts.

The good news is that a private limited company can usually change its accounting reference date by filing the appropriate notice with Companies House. However, there are rules around when and how often the date can be changed, and changing it can also alter the deadline for filing accounts. This guide explains how the process works, when changing an accounting reference date makes sense, what restrictions apply and what company directors should check before making the change.

What Is an Accounting Reference Date?

An accounting reference date is the date on which a company’s financial year normally ends. For example, if a company has an accounting reference date of 31 December, its accounting period will generally end on 31 December each year. The date is important because Companies House uses it to determine when the company's annual accounts are due. For a typical private limited company, accounts are generally due nine months after the end of the accounting period.

So, a company with a 31 December year-end would normally have until 30 September of the following year to file its annual accounts, assuming the standard private-company deadline applies. The ARD should not be confused with the company's corporation tax accounting period. Companies House and HMRC operate separate filing systems and deadlines, even though the company's accounts may be relevant to both.

Why Would a Company Change Its Accounting Reference Date?

Changing the year-end is not something most companies need to do regularly, but there are legitimate reasons for doing it.

To align with a parent company

A subsidiary may want its financial year-end to match that of its parent company. For example, a UK subsidiary of an international group might currently have a 31 March year-end while its parent reports on 31 December. Aligning reporting periods can make group consolidation easier.

To simplify group reporting

Businesses with several companies sometimes prefer a common year-end so management accounts, budgets and consolidated financial statements can be prepared on a consistent timetable.

To avoid a particularly busy period

A seasonal business may prefer to finish its financial year shortly after its busiest trading period. For instance, a retailer might choose a year-end that better reflects the completion of its main trading cycle.

To accommodate a change in the business

A company going through an acquisition, restructuring or change in ownership may decide that a different year-end is more practical.

To improve financial planning

Some businesses choose a year-end that fits more naturally with their budgeting, operational or reporting cycles. The important point is that the decision should be made for a genuine business or reporting reason rather than simply because another date appears more convenient.

How to Change an Accounting Reference Date at Companies House

The process is relatively straightforward. A company normally changes its accounting reference date by filing form AA01 with Companies House. The form is used to give notice of a change to the company's accounting reference date. Depending on how the change affects the company's accounting period, the resulting period may become longer or shorter than the company's previous financial year.

Step 1: Check the company's current accounting reference date

Before making any change, check the company's existing information on the Companies House register. You should establish:

• The current accounting reference date
• The date the company's latest accounts were made up to
• The deadline for the next accounts
• Whether the company has previously changed its accounting reference date
• Whether any accounts are currently overdue

This is an important first step because changing the date does not simply erase existing filing obligations.

Step 2: Decide on the new accounting reference date

Choose the date that best fits the company's reporting requirements. Consider:

• The company's financial cycle
• Parent or group reporting requirements
• Seasonal trading patterns
• Accountant availability
• Tax planning
• Internal budgeting
• Existing accounts deadlines

For example, changing from 31 December to 31 March may make sense for a business whose management reporting and group accounts are already structured around the UK tax year.

Step 3: Check whether the change is permitted

Companies House rules place restrictions on accounting reference date changes. A company will generally be able to change its accounting reference date by giving notice before the filing deadline for its accounts. There are also restrictions on repeatedly changing the date.

As a general rule, a company can change its accounting reference date as often as it wishes within the relevant limits, but it normally cannot make another change within five years unless one of the permitted exceptions applies. This is one reason it is sensible to check the company's filing history before submitting a change.

Step 4: File form AA01

The company must notify Companies House of the change using the appropriate procedure. For eligible companies, the change can be made electronically through Companies House online filing services. Where online filing is unavailable or inappropriate, the relevant paper form can be used. The filing should contain the company's details and the new accounting reference date. Companies House will then update the company's public record if the filing is accepted.

Step 5: Recalculate the accounts deadline

This step is easy to overlook. Changing the accounting reference date can change the date on which the company's accounts are due. For example, imagine a private limited company currently has a year-end of 30 June. Its accounts might normally be due nine months later, on 31 March.

If the company changes its accounting reference date to 31 December, its next accounting period and filing deadline may change accordingly. The exact result depends on the company's existing accounting period and the date on which the change is made. Do not assume that the new deadline is simply nine months after the new year-end without checking the transitional period created by the change.

Can You Change the Accounting Reference Date Online?

Yes. Companies House provides online services for a range of company filings, and eligible companies can submit changes electronically. Online filing is often quicker and reduces the risk of errors associated with manually completing forms.

However, the availability of online filing can depend on the company's circumstances and the particular filing being made. The safest approach is to use the current Companies House filing service or guidance when submitting the change rather than relying on an old form or third-party instructions.

What Happens After You Change the Accounting Reference Date?

The change affects the company's accounting timetable. The most important consequence is the creation of a new accounting period. Depending on the direction of the change, the company's next accounting period could be:

• Shorter than usual
• Longer than usual
• Structured around a new year-end

For example, suppose a company moves its year-end from 31 March to 31 December. The company may have a transitional accounting period running from the previous year-end through to the new December year-end. That transitional period needs to be reflected correctly in the accounts.

Example

Imagine:

Old year-end: 31 March 2026
New year-end: 31 December 2026

The company could have an accounting period running from 1 April 2025 to 31 December 2026, depending on the circumstances and timing of the change. This illustrates why directors should not treat an ARD change as merely changing a date on the Companies House profile. The accounting period itself needs to be understood and the company's accountant should ensure the accounts are prepared for the correct period.

Important Rules When Changing an Accounting Reference Date

You cannot use an ARD change to avoid filing accounts

Changing the year-end does not automatically remove an existing filing obligation. If accounts are already due, directors should deal with that obligation rather than assuming that changing the ARD will reset the clock. This is particularly important where accounts are already overdue.

The five-year restriction matters

A company generally cannot change its accounting reference date again within five years unless an exception applies. There are circumstances where a further change can be permitted, including certain situations involving group companies. Because these rules can be technical, companies that have changed their year-end recently should check their eligibility before submitting another change.

The change can affect the length of an accounting period

Directors should check whether the proposed change creates an unusually long or short accounting period. This can have practical consequences for accounting work, financial reporting and taxation.

Companies House and HMRC deadlines are different

One of the most common misunderstandings is assuming that changing the Companies House accounting reference date automatically changes every tax deadline. It does not. HMRC deals with corporation tax separately. A company may therefore need to consider whether its corporation tax accounting period and tax return obligations are affected by the new reporting arrangements. A director should speak to an accountant or tax adviser if the change creates a complex or extended accounting period.

What If Your Company Has Overdue Accounts?

This is where additional caution is needed. If a company has failed to file its accounts by the deadline, changing its accounting reference date is not a substitute for filing the overdue accounts. Late filing can result in a financial penalty from Companies House. Continued failure to file can create more serious consequences, including the possibility of the company being struck off the register.

Directors should therefore deal with overdue accounts promptly. If the company is already in default, changing its year-end without understanding the existing filing position could create further confusion rather than solving the problem.

Does Changing the ARD Affect Corporation Tax?

Potentially, yes, but not in the same way that it affects Companies House filings. Companies House filing obligations and corporation tax obligations are separate. HMRC determines corporation tax accounting periods under its own rules. A change in the company's financial year-end can therefore require the company and its accountant to reconsider the tax reporting timetable.

For example, an extended Companies House accounting period may not correspond to a single corporation tax accounting period. A company may have to prepare more than one corporation tax return even though it prepares one set of statutory accounts for Companies House. This is an area where professional tax advice can be valuable.

Should a Small Company Change Its Year-End?

There is no universal "best" accounting reference date. For a straightforward owner-managed business, the existing year-end may work perfectly well. A change may make sense when there is a clear operational advantage. Before changing it, ask:

1. Why are we changing it?
2. Will it simplify reporting?
3. Will our accountant need to prepare a short or extended set of accounts?
4. What happens to our Companies House filing deadline?
5. Does it affect our corporation tax timetable?
6. Have we changed the ARD within the last five years?
7. Are any accounts currently overdue?

If the answers are unclear, obtain accounting advice before filing the change.

Common Mistakes When Changing an Accounting Reference Date

Choosing a date without checking the filing deadline

A new year-end can create a different accounts deadline. Always calculate the consequences before submitting the change.

Assuming Companies House changes HMRC records

It does not. Companies House and HMRC have separate responsibilities.

Forgetting about the transitional period

The first accounts following an ARD change may cover a different length of time than the company's usual financial year.

Changing the date repeatedly

The five-year restriction can prevent another change unless an exception applies.

Trying to use the change to fix overdue accounts

An ARD change does not remove an existing filing default.

Updating Companies House but not internal records

The company's accounting software, management reporting calendar, budgets and tax planning should all reflect the new financial year.

Companies House, Accountants and Company Formation Platforms

Companies House is responsible for maintaining the public register of UK companies and receiving statutory filings. The company's directors remain legally responsible for ensuring that required information and documents are filed correctly and on time.

An accountant can help determine whether a new accounting reference date makes financial and tax sense, while a company formation and management platform such as IncorpUK can be useful for founders who want help managing routine UK company administration. For overseas founders, this distinction is particularly useful: having someone assist with administration does not remove the directors' underlying legal responsibilities.

FAQ: Changing a Company’s Accounting Reference Date

Can I change my company's accounting reference date?

Yes. A UK company can generally change its accounting reference date by notifying Companies House using the appropriate filing procedure, subject to the rules governing when and how often changes can be made.

How do I change my accounting reference date at Companies House?

The standard process involves notifying Companies House using form AA01 or the applicable online filing service. The company's new accounting reference date must be provided.

How often can I change my accounting reference date?

There is generally a five-year restriction on changing the accounting reference date again, although exceptions can apply. Check the company's previous filing history and the current Companies House rules before making another change.

Can I change my accounting reference date if my accounts are overdue?

An ARD change does not remove an existing obligation to file overdue accounts. If accounts are already late, the company should address the filing default separately.

Does changing my year-end change my Corporation Tax deadline?

Not automatically. Companies House and HMRC have separate filing systems and rules. A change in the company's financial year may affect tax reporting, but the consequences should be assessed separately.

Can I change my year-end to match my parent company?

Yes, aligning a subsidiary's year-end with a parent company's reporting period can be a legitimate reason for changing an accounting reference date, subject to the applicable Companies House rules.

Can an accounting period be longer than 12 months?

A change in accounting reference date can result in an accounting period longer or shorter than 12 months, subject to statutory rules. Longer periods can have additional accounting and tax implications.

Does changing the accounting reference date cost anything?

The filing itself may not carry a separate Companies House fee in the same way as certain other company applications, but professional accountants or company administration providers may charge for preparing the change and dealing with the resulting accounts and tax work.

Will the public see my company's new accounting reference date?

Yes. Companies House maintains a public company register, and the company's filing information and accounting details can be viewed through the register.

Conclusion

Changing a company's accounting reference date can be a sensible move when the existing financial year no longer fits the business. It can simplify group reporting, align a subsidiary with its parent company or better reflect the company's trading cycle. But the process should not be treated as a simple administrative date change.

Before filing, check the company's current ARD, previous changes, outstanding accounts and proposed new reporting period. Most importantly, understand how the change will affect the next accounts deadline and whether separate action is required with HMRC.

For straightforward companies, changing the ARD can be relatively simple. For businesses with overdue filings, group structures, unusual accounting periods or complex tax arrangements, professional advice is worth considering. The best time to change a company's year-end is before the existing timetable becomes a problem. A little planning can prevent a surprisingly large amount of accounting and filing confusion later.