Accounting Reference Date Explained

Every UK company has to prepare and file annual accounts, and that starts with understanding your accounting reference date. This date marks the end of your company’s financial year and determines when your accounts are due. But how is it set, can you change it, and how does it relate to your deadlines with HMRC and Companies House?

Here’s everything you need to know.

What Is the Accounting Reference Period?

The accounting reference period is the financial reporting period that a company uses to prepare its annual accounts. It typically lasts 12 months and ends on the company’s accounting reference date.

This period is important because it defines the timeframe your accounts will cover — for example, income, expenses, assets and liabilities over the course of your financial year.

What Is the Accounting Reference Date?

The accounting reference date (ARD) is the official end of a company’s financial year for Companies House purposes. It marks the final day of the accounting reference period and is used to calculate filing deadlines.

For most UK companies, the ARD automatically falls on the last day of the month in which the company was incorporated, unless it's been changed.

Example:

If your company was incorporated on 15 March 2024, your first accounting reference date would be 31 March 2025. Your financial year would run from 15 March 2024 to 31 March 2025 — slightly longer than a full calendar year for the first set of accounts.

Can You Change an Accounting Reference Date?

Yes, you can change your company’s accounting reference date. This is done by filing a request with Companies House, either online or by post.

You can:

• Shorten the accounting period as often as you like

• Extend it only once every five years, unless there’s a valid reason (like aligning with a parent company’s year end)

You can’t extend a period if your accounts are already overdue.

Changing your ARD can be useful if you want to align your financial year with the tax year (ending 5 April) or for practical business reasons — such as syncing accounts across a group of companies.

Is There a Difference Between the Accounting Reference Date and a Company’s Financial Year End?

In most cases, the accounting reference date is the same as the financial year end.

The ARD is the formal term used by Companies House, while “financial year end” is a broader term often used internally or in management accounts. Both refer to the last day of the company’s accounting period.

However, in some cases, a company may choose to produce management accounts or internal reports based on different dates (e.g. quarterly or calendar year), which don’t affect the statutory ARD.

What Happens at the End of a Company’s Financial Year?

At the end of your financial year (your ARD), your company needs to prepare:

• Annual accounts (statutory accounts)

• A company tax return for HMRC

• Any required audit or internal reviews (if applicable)

The financial year end is the cut-off point for your income and expense reporting. It’s the date your accountant or finance team uses to finalise figures, calculate profits, and work out corporation tax owed.

The accuracy and timing of this process are crucial — late or incorrect submissions can lead to penalties.

Deadlines for Submitting Annual Accounts to HMRC and Companies House

Your deadlines depend on whether you’re submitting your first accounts or subsequent annual accounts.

For Companies House:

• First accounts: Due 21 months after incorporation

• Subsequent accounts: Due 9 months after the ARD

For HMRC:

• You must submit your Company Tax Return (including statutory accounts) within 12 months of your financial year end

• However, you must pay any Corporation Tax due within 9 months and 1 day of your year end

Example:

If your company year end is 31 March 2025:

• Your Companies House deadline: 31 December 2025

• Your Corporation Tax payment deadline: 1 January 2026

• Your Company Tax Return filing deadline: 31 March 2026

It’s a common mistake to assume the same deadline applies to both HMRC and Companies House — but they’re separate, and both must be met.

Final Thoughts

Your accounting reference date sets the foundation for your company’s financial reporting timeline. Understanding how it works — and how it aligns with your tax responsibilities — helps you stay compliant and avoid fines.

You can change your ARD if needed, but you’ll still need to hit key submission deadlines with both Companies House and HMRC. If you're not sure when your next filings are due or whether you should adjust your year end, it’s worth getting advice from your accountant.