Self Assessment accountant in London
We prepare and file your Self Assessment return, built from your records and checked with you before 31 January.
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The Self Assessment tax return deadline, the VAT return deadline, the Corporation Tax return deadline and Companies House dates, set out in one place.
Most small businesses do not miss a tax return deadline because the work is hard. They miss it because there are several different dates, they move with your accounting period, and nobody is tracking all of them at once. This guide puts every tax return deadline that applies to a sole trader, landlord or limited company in one place.
If a deadline has already passed, our guide to what happens when you have missed the Self Assessment deadline explains the penalties and what to do next.
The tax year runs from 6 April to 5 April. Your Self Assessment deadlines all count from the end of that tax year:
When people ask when the Self Assessment tax return is due, they almost always mean 31 January, because almost everyone files online. That is also the deadline for a self-employed tax return, since sole traders and freelancers file through Self Assessment. Payments on account are due on 31 January and 31 July, so January can mean paying last year's balance and the first instalment for the current year at the same time.
Our Self Assessment tax returns page explains what we do for you between now and each of these dates.
If you are registered for VAT, you usually send a VAT return every 3 months, so quarterly VAT return deadlines are the norm. The VAT return deadline is one calendar month and 7 days after the end of each VAT period: that is both the VAT return submission deadline and the due date for payment. For a quarter ending 30 June, both are due on 7 August.
Your VAT periods depend on when you registered, so they do not always line up with calendar quarters. Late VAT returns earn penalty points, and reaching the threshold brings a £200 penalty. Our VAT returns page covers registration, the schemes and how penalties work.
A limited company has two separate Corporation Tax dates, and they are easy to confuse because the payment comes first:
So for a company with a 31 March year end, the tax is due by 1 January and the Corporation Tax return deadline is 31 March the following year. Filing the return late brings a £200 penalty after one day, another £200 at 3 months, and 10% of any unpaid tax at 6 and 12 months.
Private companies must also file annual accounts at Companies House within 9 months of the year end. This is a separate filing from the Company Tax Return, with its own penalties: £150 if accounts are up to a month late, rising to £1,500 if they are more than 6 months late, and doubled if they are late two years in a row.
In practice the year-end accounts and the Corporation Tax return are prepared together, so the 9-month Companies House deadline is the one to plan around. Our year-end accounts and Corporation Tax page explains how we work to it.
If you employ anyone, including yourself as a director on a salary, payroll has its own rhythm:
See payroll services for how we run it.
We work out every deadline that applies to you, from your tax year, VAT periods and company year end.
Reconciled monthly books turn each return into a check rather than a scramble.
We prepare returns well before each deadline, so you know what you owe in good time.
We file, confirm the payment dates and tell you what is coming next.
31 January after the end of the tax year for online returns, and 31 October for paper returns. For the 2025/26 tax year, the online deadline is 31 January 2027.
For most people it is 31 January, the online Self Assessment tax return deadline. Tax owed is due the same day.
One calendar month and 7 days after the end of the VAT period. The payment is due by the same date.
The Company Tax Return is due within 12 months of the end of the accounting period, but the tax itself is due 9 months and 1 day after it.
By 31 January after the end of the tax year if you file online, the same Self Assessment deadline as everyone else.
File as soon as you can, because penalties grow over time. Our guide to the missed Self Assessment deadline explains the next steps.
Keep reading
Book a free 20-minute call and we will list every deadline that applies to you and agree who does what.