When is my company's first year end?

Automatically, the last day of the month of your first anniversary of incorporation. Incorporate on 10 July 2026 and your accounting reference date is 31 July, with a first period running 10 July 2026 to 31 July 2027. You can change the year end if a different date suits — 31 March is popular because it aligns with the tax year.

Why do I need two Corporation Tax returns in year one?

A CT600 can cover a maximum of 12 months, but the first accounting period usually runs a few weeks longer (incorporation date to month-end a year later). HMRC therefore splits it: one return for the first 12 months, a second for the remaining stub — each with its own payment date. One set of accounts covers both.

When are my first accounts due at Companies House?

21 months after incorporation (for a first period longer than 12 months). After that first filing, the normal rule applies: 9 months after each year end.

Should I change my accounting reference date?

Sometimes. Aligning to 31 March simplifies the interaction with tax-year-based rules; a quieter month for your trade can make year-end admin easier; and lengthening or shortening a period can occasionally smooth a tax outcome. Change it deliberately, not accidentally — and note you generally can't lengthen a period more than once every 5 years.

Your Company's First Year | Accounts & Tax Timeline

Limited company accounts and Companies House filing, in navy and gold

A worked first-year timeline

Company incorporated 10 July 2026, starts trading immediately:

~24 July 2026 — UTR letter arrives; register for Corporation Tax (within 3 months of starting business)
24 July 2027 — first confirmation statement due (12 months + 14 days)
31 July 2027 — first year end (last day of anniversary month)
10 April 2028 — first accounts due at Companies House (21 months after incorporation), and Corporation Tax payment due for the first 12 months of the period (9 months + 1 day after 9 July 2027)
1 May 2028 — Corporation Tax payment due for the stub period (9 months + 1 day after 31 July 2027)
9 July / 31 July 2028 — the two CT600 returns due (12 months after each period ends)

Notice the shape: nothing for a year, then everything lands in a few weeks. This is why new directors get caught out — and why sensible ones have the accounts prepared within a couple of months of the year end, long before any deadline.

Why year one has two tax returns

A Company Tax Return can cover at most 12 months. Your first accounting period is almost always a little longer (10 July 2026 → 31 July 2027 is 12 months and 3 weeks), so HMRC splits it into a 12-month return and a short stub return. It’s one set of accounts, one job for your accountant — but two filings and two payment dates to hit. After year one, you’re on the normal single-return cycle.

The ongoing Corporation Tax deadlines

What to do during the year (not at the end)

Keep bookkeeping current — a year of receipts reconstructed in a weekend produces expensive accounts
Document every dividend when paid (minute + voucher)
Put money aside for Corporation Tax as profits arise — 19–25% of profit is HMRC’s
Review salary/dividend mix before the tax year ends on 5 April, while it can still be changed

The full new-company checklist

First year end approaching?

We prepare first-year accounts and both CT600s as one job, confirm each payment date, and set the routine for every year after. Call 0114 327 1480.

First-year accounts service

Your company’s first year: accounts and tax