Bookkeeping and tax filing in the UK follow a predictable calendar set by HMRC and Companies House. Once you can see the whole year laid out, the surprises disappear. So this guide walks through a typical year for a small UK business, season by season, so you can see how the deadlines fit together.
Imagine you run a small limited company with a 31 March year end. You are VAT registered on calendar quarters, you employ a few staff and, as a director, you also file a personal Self Assessment return.
Spring, when the new year begins
The income tax year starts from 6 April 2026 and runs to 5 April 2027. Your company’s financial year has just closed on 31 March, so spring is the moment to tidy the books. Reconcile the bank and make sure every receipt is recorded.
Spring also brings a VAT deadline. The return for the quarter ending 31 March is due by 7 May, because VAT returns and payments are due 1 calendar month and 7 days after the end of each period. Every employee must receive their P60 by 31 May.
For sole traders and landlords, this spring was a turning point. From 6 April 2026, Making Tax Digital for Income Tax became mandatory for those with qualifying income over £50,000, replacing once a year bookkeeping with digital records and quarterly updates. The threshold is planned to fall to £30,000 from April 2027.
Summer, when the reporting starts to stack up
Summer is busier than many people expect. P11D forms for staff benefits are due by 6 July, and any Class 1A National Insurance must be paid by 22 July. The second payment on account for 2025/26 is due on 31 July 2026.
August brings two deadlines on the same day. The VAT return for the quarter ending 30 June is due by 7 August, and sole traders under Making Tax Digital must send their first quarterly update by 7 August as well.
Autumn, the calm before the busy season
Autumn is quieter, which makes it the best time to get ahead. Anyone who started a business in the 2025/26 tax year must register for Self Assessment by 5 October 2026, and paper returns are due by 31 October. The next VAT return and Making Tax Digital update both fall due on 7 November.
This is also when a smart business owner books time with their accountant. Your company’s year end accounts are due at Companies House by 31 December, and leaving them late is how penalties happen.
Winter, when the big deadlines land
Winter is where the calendar gets serious. Private companies must file annual accounts with Companies House within 9 months of the year end, which means 31 December 2026 for a 31 March year end. Corporation Tax payment follows 1 day later, on 1 January 2027, because it is due 9 months and 1 day after the year end (not the CT600).
Then comes 31 January 2027, the most famous date in the UK tax calendar. By this date, your online Self Assessment return for 2025/26 must be filed, any balancing payment made and your first payment on account for 2026/27 paid. A week later, on 7 February, the next VAT return and Making Tax Digital update are due.
The year closes as it began. Your Company Tax Return (CT600) for the year ending 31 March 2026 must be filed by 31 March 2027, twelve months after the year end, and a new year end arrives the same day.
The deadlines that never stop
Some obligations run all year round. If you employ staff, a Full Payment Submission must reach HMRC on or before every payday, and PAYE and National Insurance must be paid by the 22nd of the following tax month when paying electronically. Your company must also file a confirmation statement at least once every 12 months, within 14 days of its review date.
Why missing a deadline costs more than you think
Penalties start small and grow. A late Self Assessment return brings an automatic £100 penalty, with more charges after 3, 6 and 12 months. A late CT600 also starts at £100. Late accounts cost a private company between £150 and £1,500 at Companies House, and late VAT returns build up penalty points that lead to a £200 fine. Interest is added on any tax paid late.
The common thread is bookkeeping. Businesses that record transactions and reconcile the bank every month rarely miss deadlines, because the figures are always ready. Keep those records safe too, for at least 6 years for a company and at least 5 years after the 31 January deadline for a sole trader.
How RnD Accountants keeps your calendar under control
RnD Accountants is a firm of licensed CIMA Chartered Management Accountants based in London, supporting UK small and medium businesses since 2013. We handle bookkeeping, VAT, payroll, Making Tax Digital, annual accounts, Corporation Tax and Self Assessment, so every date in this calendar is met on time.
Book a free initial consultation and we will map out your own bookkeeping and tax filing calendar.
Map Out Your Bookkeeping and Tax Filing Calendar
Speak with our London team of licensed CIMA Chartered Management Accountants to ensure every HMRC and Companies House deadline is met on time.
Book a Free Consultation→Key Takeaways
- ✓The 2026/27 UK tax year runs from 6 April 2026 to 5 April 2027; limited company accounts, Corporation Tax, and CT600 follow your specific year end.
- ✓From 6 April 2026, Making Tax Digital (MTD) mandates quarterly digital updates for sole traders and landlords with income over £50,000.
- ✓Seasonal deadlines: VAT returns fall quarterly (7 May, 7 Aug, 7 Nov, 7 Feb); staff P60s by 31 May; P11D benefits by 6 July.
- ✓Winter peaks with Companies House accounts (31 Dec), Corporation Tax (1 Jan), and online Self Assessment (31 Jan).
- ✓Continuous monthly bank reconciliation and maintaining records (5 to 6 years) prevent escalating penalties and interest.
Common Questions
Do I need an accountant for bookkeeping and tax filing?
It is not a legal requirement, but an accountant reduces the risk of errors, missed deadlines and penalties, and often finds tax savings.
Do my deadlines change if my year end is not 31 March?
Yes. Company accounts, Corporation Tax and CT600 deadlines all move with your year end, while Self Assessment, VAT and payroll dates follow their own fixed cycles.
