UK Tax Deadlines 2025/26 | Barton Accountancy

Tax deadlines

Miss a deadline, pay a penalty.

UK tax runs on a strict deadline calendar. Miss one and HMRC or Companies House start charging penalties automatically. Most of these are trivial when you know they're coming, and expensive when they sneak up.

The key dates

Deadlines that matter.

Everything is included in your fixed monthly fee. No extras, no surprises.

31 January

Self assessment tax return + first payment on account due. Late filing £100+.

5 April

Tax year-end. Last day for ISAs, pension allowance and dividend allowance.

19 April

Final FPS of the tax year (PAYE). Plus CIS return for March.

31 May

P60s must be given to employees.

6 July

P11D benefits in kind forms due to HMRC.

31 July

Self assessment second payment on account due.

7 August / November / February / May

Quarterly VAT return deadlines (for standard quarterly filers).

9 months after year-end

Limited company statutory accounts due at Companies House.

12 months after year-end

CT600 corporation tax return due to HMRC.

Sound familiar?

Most businesses don't have an accountant.
They have a filing service.

If any of these ring true, you're not getting what you should be.

01

You only hear from them at year-end

No check-ins, no planning, no conversation. Just a bill and a set of accounts you don't fully understand.

02

You're never sure where you stand

Your numbers are months out of date. You're making decisions based on gut feel, not real figures.

03

Surprise invoices keep landing

An email here, a phone call there — and suddenly your bill is twice what you expected. No one told you.

Common questions

Things people ask us.

What happens if I miss a deadline?

It depends which. Companies House missed accounts: £150 climbing to £1,500. HMRC missed self assessment: £100 immediately, rising with further penalties. Missed VAT: surcharge on the tax owed. Missed CT600: £100 minimum, plus daily penalties after 3 months.

Can penalties be appealed?

Yes, if you have a 'reasonable excuse' — illness, bereavement, software failure, HMRC mistakes. Standard busyness doesn't count. We handle appeals for clients at no extra charge.

How do you make sure clients never miss a deadline?

We track every deadline for every client internally, and we chase you for information well before the deadline. Most work is filed days or weeks early, not at the last minute.

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