Setting a company accounting reference date

A company's accounting reference date marks the end of its financial year for Companies House accounts. It is not automatically the same as a personal tax year end or the period covered by a Corporation Tax return. Keep these dates distinct when planning the first year's reporting.

Understand the initial date

Companies House normally sets an accounting reference date at the end of the incorporation month in the following year. The first accounts therefore commonly cover more than twelve months. Check the actual date shown on the company record. ^[1]

For illustration, a company incorporated part-way through June may have its first financial year end at the end of the following June. Do not use the incorporation anniversary as the assumed end date without checking the record.

Consider whether a different year end is useful

Some businesses prefer a year end aligned with a trading season, a wider group or an existing bookkeeping cycle. Explain the commercial reason to the accountant before making the change.

A change can affect filing periods, preparation workload and tax-return arrangements. It is not merely a cosmetic edit to the company profile.

Check the rules before changing it

Companies House allows changes within its stated limits and conditions. Restrictions apply to extending accounting periods and to periods for which accounts are already overdue. Read the current process and confirm the effect on the filing deadline before submitting a change. ^[2]

Avoid changing the date at the last moment in the hope of resolving an overdue filing. Ask for a written schedule of the periods and deadlines that will apply after the change.

Keep the Corporation Tax periods separate

A Corporation Tax accounting period cannot be longer than twelve months. A first financial period or extended set of accounts may therefore require more than one tax return and payment deadline. ^[1][3]

The accountant needs both the incorporation date and the date the company became active. The correct tax periods cannot always be determined from the Companies House year end alone.

A year-end decision checklist

• Confirm the current accounting reference date and filing deadline.
• Explain the reason for any proposed change.
• Review whether the change is permitted.
• Map the resulting accounts and tax periods.
• Update internal deadlines and adviser instructions.

Sketch the first periods on paper

Take an illustrative company incorporated on 15 June 2026 with an unchanged first accounting reference date of 30 June 2027. Its first Companies House accounts would normally start at incorporation and run to that year end. If it starts the relevant business activity later, the Corporation Tax periods need to be considered using that later fact as well. ^[1]

Write the incorporation date, activity start and proposed year end on separate lines. Ask the accountant to confirm the tax periods and payment dates that follow. This avoids using the same phrase first year to describe several different periods without realising it.

Do not infer that an accounts period extending beyond twelve months allows one equally long Corporation Tax return. Equally, do not assume that every new company necessarily needs two tax returns without checking when its tax accounting period begins. The actual dates determine the work required.

Compare the commercial reasons for a change

A seasonal retailer might prefer to prepare accounts after its busiest selling period, while a subsidiary may need dates aligned with its parent. Explain the reason and ask what the change means for stock counts, record preparation, management comparisons and professional fees. A date that looks convenient on the calendar may create an unusually short or long reporting period.

Prepare a before-and-after schedule. Include the old and proposed period ends, the affected accounts, the filing dates and relevant tax actions. Mark any deadline that becomes earlier. The directors should see these consequences before approving the change, especially if records are not yet ready.

Check the limits and the timing

Current Companies House guidance normally limits a lengthened financial year to eighteen months and lengthening to once in five years, subject to specified exceptions. It also prevents changing the year end while accounts are overdue. Check whether the actual proposal fits the rules before treating the change as available. ^[2]

Avoid using an extension as an assumed solution to an imminent filing problem. Changing the first financial year end does not necessarily give the extra filing time a founder expects. Ask for the exact resulting deadline and keep the official acceptance evidence.

Complete both the filing and the handover

Once the change is accepted, update the internal diary, bookkeeping period and adviser instructions. Government guidance also requires the relevant Corporation Tax accounting-period dates to be updated with HMRC when the financial year is shortened or lengthened. Confirm that this step is dealt with rather than assuming a Companies House update automatically finishes the tax work. ^[2]

Retain the old schedule for context and mark the new one as current. If the accountant changes later, include the year-end change history in the handover so the replacement adviser can understand why the first accounts and tax periods do not match a standard twelve-month pattern.

Keep the acknowledgement of the change and confirm that the company record reflects it. Then update the bookkeeping calendar so records are prepared for the correct period, not the superseded date.

For assistance organising the proposed accounts dates and responsibilities, see new company compliance planning.