A new company's first accounts and first Company Tax Return

When a company is set up, it gets different reporting dates for its first annual accounts and its first Company Tax Return. The first accounts usually cover more than 12 months, because they start on the day the company was incorporated and end on the accounting reference date that Companies House sets for the end of its financial year.

GOV.UK's example: a company set up on 11 May has an accounting reference date of 31 May the following year, so its first accounts must cover 12 months and 3 weeks. In later years the accounts normally cover the financial year from 1 June to 31 May.

The first accounts are due 21 months after the date the company registered with Companies House. In law, when the first period is longer than 12 months, the deadline is the later of nine months after the first anniversary of incorporation and three months after the period ends. When it is not longer than 12 months, the usual nine months after the period ends applies.

The period a tax return covers, which is the accounting period for Corporation Tax, cannot be longer than 12 months. So the period of the first accounts may need two tax returns, with two payment deadlines.

GOV.UK's example: a company set up on 11 May 2024, whose first accounts end on 31 May 2025, has these payment deadlines.

• 11 February 2026, for the period from 11 May 2024 to 10 May 2025
• 1 March 2026, for the period from 11 May 2025 to 31 May 2025

Each date is nine months and one day after its accounting period ends. In later years the company normally files one return, which usually covers the same financial year as its accounts.

How many returns the company files, and their dates, depend on whether it started trading the day it was set up or later. A company is usually dormant for Corporation Tax between being set up and starting to trade. It tells HMRC the day it started to trade when it adds Corporation Tax services to its business tax account, and its first accounting period starts from that day.

• Trading from the day it was set up

  Two returns, one for the first 12 months and one for the rest of the time the first accounts cover. In GOV.UK's example the company is set up and starts trading on 11 May 2024, with accounts to 31 May 2025: the returns are for 11 May 2024 to 10 May 2025 and for 11 to 31 May 2025.

• Trading later, Corporation Tax services added in time

  Added before the accounting reference date, the company usually has no return to file for the dormant period, and files one for the trading period, or two if it traded for more than 12 months. In GOV.UK's example the company is set up on 11 May 2024, starts trading on 22 July 2024, adds the services on 26 August 2024 and has an accounting reference date of 31 May 2025: one return, for 22 July 2024 to 31 May 2025.

• Trading later, services not added in time

  Two returns, one for the dormant period and one for the trading period. With the same dates and no services added before 31 May 2025, they are for 11 May to 21 July 2024 and for 22 July 2024 to 31 May 2025.

In every case the accounts are one set, from the day the company was set up to the accounting reference date. After the first year, the company's accounts and returns normally follow its financial year. GOV.UK also says to check the notice to deliver a Company Tax Return that HMRC sends after the first year: if it covers the dormant and trading periods, two returns are needed.

• The accounting period dates in HMRC's letter, which it sends after the company adds Corporation Tax services. Tell HMRC if they look wrong.
• The company's year end, if it has been lengthened or shortened. After lengthening a financial year, HMRC has to be told the new accounting period dates before the original filing date of the return, or a late filing penalty may follow.
• The payment date for each accounting period, which is its own date and not the same as the accounts date.

The dormant companies guide covers what a company files while it is dormant, and the filing deadlines page the rules for each date.

This service works out the accounting periods from the company's year end and incorporation date, and splits a long first period into accounting periods of up to 12 months, each with its own computation, CT600 values and dates.

It takes the first accounting period to start on the day the company was incorporated. A company that started to do business later has to check its dates with HMRC's letter or its accountant.

A qualified accountant has not reviewed the calculations. Treat the output as a working draft for you or your accountant to check.