If you run a limited company in the UK, you may find that your current accounting reference date (ARD) no longer suits your business needs. Whether you’ve recently acquired a subsidiary, gone through a restructure, or simply want to align your year-end with the tax calendar, knowing how to change your accounting reference date — and doing so correctly — can make a significant difference to your compliance obligations and financial planning.
In this guide, the expert team at Accounting Crunchers — one of the leading accounting firms in UK — walks you through everything you need to know about changing your accounting reference date, from what it means and why it matters, to the step-by-step process for notifying Companies House.
What Is an Accounting Reference Date (ARD)?
Your Accounting Reference Date (ARD) is the date on which your company’s financial year ends. It determines when your annual accounts must be prepared and filed with Companies House, and it also influences your Corporation Tax deadlines with HMRC.
By default, when a company is incorporated in the UK, its ARD is set to the last day of the month in which the company was formed, falling one year after incorporation. For example, if your company was incorporated on 15th March, your ARD would initially be set to 31st March of the following year.
Understanding your ARD is fundamental to staying compliant. Missing your filing deadlines can result in automatic penalties — a situation that the best accountants near me and across the UK help their clients avoid every day.
Why Would You Want to Change Accounting Reference Date?
There are several legitimate and strategic reasons why a business might want to change its ARD:
- Aligning with a parent or group company: If your business has been acquired or has become part of a larger group, aligning your year-end date with the rest of the group simplifies consolidated reporting and reduces administrative burden.
- Seasonal businesses: Companies with highly seasonal revenue — such as hospitality, retail, or agriculture — may benefit from a year-end that falls after their peak trading period. This gives a more accurate snapshot of the business’s financial health.
- Tax planning opportunities: Changing your ARD can affect the timing of Corporation Tax payments and potentially allow you to take advantage of changes in tax rates or allowances. This is a nuanced area, and consulting accountants in London UK or elsewhere is strongly advised.
- Simplifying the filing process: Some companies — particularly newly incorporated ones — find themselves with awkward short accounting periods that result in two sets of accounts needing to be filed. Adjusting the ARD can consolidate this into a single, cleaner annual filing.
- Cash flow management: A well-chosen year-end can help with cash flow forecasting and budgeting cycles, especially when payroll, VAT quarters, and trading patterns are all considered together.
The Legal Framework: What Does the Law Say?
The rules around changing your ARD are governed by Section 392 of the Companies Act 2006. This legislation gives limited companies the right to modify their financial year-end, but within a clearly defined set of restrictions.
Here is a summary of the key rules you need to be aware of:
Extending Your Accounting Period
- You can extend your financial year to a maximum of 18 months from the start of the accounting period.
- You can only extend your ARD once every five years, unless an exception applies (such as the company being in administration, aligning with a parent company, or special circumstances approved by Companies House).
- The extension applies to the current financial year or the immediately preceding one.
Shortening Your Accounting Period
- There is no limit on how many times you can shorten your accounting year.
- Shortening can also be used tactically — if you are struggling to meet a filing deadline, shortening the accounting period by even a few weeks grants an additional three months to file.
When You Cannot Change Your ARD
- You cannot change your ARD for a period for which your accounts are already overdue.
- The change must relate to the current or immediately preceding accounting period only.
Navigating these rules can be complex, particularly when planning multi-year restructuring. This is where engaging one of the experienced accounting firms in UK — like Accounting Crunchers — becomes invaluable.
How to Change Your Accounting Reference Date: Step-by-Step
The process of changing your ARD is handled through Companies House. Here is how it works:
Step 1: Decide on Your New ARD
Before filing anything, you need to decide on the most appropriate new year-end date for your business. Consider your business cycle, any group reporting requirements, your VAT quarters, and the tax implications. Speaking with accountants in London UK or your local area at this stage is strongly recommended.
Step 2: Complete Form AA01
To officially change your ARD, you need to submit Form AA01 — the Change of Accounting Reference Date form — to Companies House. This form requires you to confirm:
- Your company name and registration number
- Whether you are shortening or extending the accounting period
- The new ARD you wish to adopt
- The reason for the extension, if applicable (e.g., aligning with a parent company or special circumstances)
Step 3: File Online or by Post
You can submit Form AA01 through the Companies House WebFiling service, which is the quickest and most straightforward method. Alternatively, you can complete a paper form and post it to Companies House at Crown Way, Cardiff, CF14 3UZ.
Step 4: Notify HMRC
It is important to understand that Companies House and HMRC are separate bodies. Changing your ARD with Companies House does not automatically update your Corporation Tax accounting period with HMRC. You will need to inform HMRC separately of the change to ensure your Corporation Tax obligations are updated accordingly. Failure to do so can lead to confusion over tax payment deadlines and potentially result in penalties.
The best accountants near me will always ensure this step is not overlooked — it is one of the most common mistakes businesses make when changing their ARD independently.
Step 5: Update Your Internal Records
Once your ARD has been officially changed, make sure your internal financial calendar is updated. This includes your payroll schedule, VAT return quarters, management accounts timetable, and any contractual reporting obligations to banks, investors, or shareholders.
Tax Implications of Changing Your Accounting Reference Date
Changing your ARD is not purely an administrative exercise — it carries real tax consequences that require careful planning.
When a company extends its accounting period beyond 12 months, HMRC treats this as two separate Corporation Tax accounting periods for tax purposes. This means you may need to file two Corporation Tax returns and make two sets of tax payments, even though Companies House only requires one set of accounts.
Shortening the accounting period can also affect tax timelines. While it might defer some liabilities, it also means a shorter period in which to offset allowances and losses. Depending on the timing, you may find that a year-end change coincides with a change in Corporation Tax rates — which is why strategic planning in advance is critical.
For businesses engaged in international operations, the implications can be even more complex, particularly where double-tax treaties and foreign fiscal calendars are involved. The chartered accountants at Accounting Crunchers — one of the top accounting firms in UK — have extensive experience advising clients across all sectors on the cross-border tax dimensions of ARD changes.
Common Mistakes to Avoid
When businesses attempt to change their accounting reference date without professional guidance, they frequently encounter the following pitfalls:
- Forgetting to notify HMRC: As mentioned above, Companies House and HMRC operate independently. Many businesses change their ARD with Companies House but forget to update HMRC, leading to mismatched deadlines and confusion.
- Attempting to extend beyond 18 months: Companies sometimes try to use a two-step process — first shortening, then extending — to engineer a period exceeding 18 months. This is not permitted; the total period cannot exceed 18 months regardless of the steps taken.
- Changing a period for which accounts are overdue: You cannot apply to change your ARD if the accounts for that period are already late. This is a common misconception that can leave businesses in a difficult position.
- Extending more than once in five years without valid grounds: Unless an exception applies, extending your ARD more than once within a five-year window is not allowed and your application will be rejected by Companies House.
- Missing the updated filing deadline: After changing your ARD, your accounts filing deadline changes too (except in your first year). Businesses sometimes miss the updated deadline simply because they did not recalculate it after the change.
How Accounting Crunchers Can Help
At Accounting Crunchers, we understand that the rules around changing your accounting reference date can feel overwhelming — particularly when you are also trying to run a business. As one of the most trusted accounting firms in UK, our team of Chartered Accountants — trained at the Big 4 — brings deep expertise to help you make the right decision for your business.
Whether you are searching for accountants in London UK to help with a group restructure, or simply want the best accountants near me to ensure your year-end change is handled compliantly and strategically, we are here to help. Our services include:
- Advising on the optimal ARD for your business cycle and tax position
- Preparing and submitting Form AA01 to Companies House on your behalf
- Notifying HMRC and updating your Corporation Tax accounting periods
- Managing your accounts preparation for any shortened or extended periods
- Ongoing compliance support, including year-end accounts, VAT returns, payroll, and Corporation Tax filings
We are based at 30 Churchill Place, Canary Wharf, London — and we work with businesses of all sizes across the UK, from sole traders and startups to established SMEs and international groups.
Final Thoughts
Changing your accounting reference date is a legitimate and often strategically valuable step for UK businesses. However, it is not without its complexities. Between the restrictions under the Companies Act 2006, the separate notifications required by HMRC, and the downstream impact on tax deadlines and cash flow, the process demands careful planning and professional execution.
If you are considering a change to your accounting reference date — or if you simply want to explore whether a different year-end might benefit your business — get in touch with Accounting Crunchers today. Our team of experts is ready to guide you through every step of the process with confidence, accuracy, and professionalism.
