When are limited company accounts due at Companies House?

Annual accounts must be filed with Companies House 9 months after the end of your company's financial year (accounting reference date). If your year-end is the last day of a month, the filing deadline is the last day of the month 9 months later. A company's first accounts are due 21 months after the date of incorporation.

When is Corporation Tax due?

For most small and medium companies, Corporation Tax must be paid 9 months and 1 day after the end of your accounting period. The Company Tax Return (CT600) must be filed with HMRC 12 months after the end of the accounting period. Large companies with profits over £1.5m pay in quarterly instalments.

When is the Self Assessment tax return deadline?

Online Self Assessment tax returns and any balancing payment are due by 31 January following the end of the tax year (5 April). Paper returns are due earlier, by 31 October. Payments on account are due by 31 January and 31 July.

UK Accounting & Tax Deadline Calculator

Enter your company's financial year-end and get the three dates that follow from it — your Companies House accounts deadline, your Corporation Tax payment date, and your CT600 filing date. Below the calculator is a full reference of the fixed UK deadlines for Self Assessment, VAT and payroll.

Your company's financial year-end

Also called your accounting reference date (ARD). For most companies this is the last day of a month — e.g. 31 March or 30 April.

Pick a year-end date above to see your deadlines.

Stop calculating these by hand

Sodium tracks every client's year-end, VAT quarter and payroll dates automatically, and generates the tasks and reminders that go with them — so nothing slips. It pulls key dates straight from Companies House and turns them into recurring tasks across your whole client base.

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The fixed UK accounting & tax deadlines

The dates above are calculated from your year-end. The deadlines below are fixed points in the UK tax calendar — the same every year, whatever your year-end. Here are the ones every practice works to.

Self Assessment (income tax)

5 October	Register for Self Assessment (if newly self-employed or newly needing to file) for the previous tax year
31 October	Paper tax return filing deadline
30 December	Online filing deadline to have tax collected through your PAYE tax code (if eligible and under £3,000)
31 January	Online tax return deadline, balancing payment, and first payment on account
31 July	Second payment on account

VAT

Under Making Tax Digital, VAT returns and payments are due one calendar month and 7 days after the end of each VAT accounting period. For a quarter ending 31 March, the return and payment are due by 7 May. Businesses on the Annual Accounting Scheme and those paying by direct debit have slightly different timings.

PAYE & payroll

On or before payday	Submit your Full Payment Submission (FPS) to HMRC each time you run payroll
22nd of the month	Pay PAYE tax and National Insurance to HMRC electronically (19th if paying by post). Quarterly for small employers.
19 April	Final submission for the tax year (FPS/EPS)
31 May	Give employees their P60 for the previous tax year
6 July	Submit P11D and P11D(b) for expenses and benefits
22 July	Pay Class 1A National Insurance on benefits (19 July if paying by post)

Companies House confirmation statement

Separate from your accounts, every company and LLP must file a confirmation statement at least once a year. It's due within 14 days of the end of your review period — usually the anniversary of incorporation or of your last statement. It confirms your registered details, officers, shareholders and people with significant control.

CIS (Construction Industry Scheme)

Contractors must file their monthly CIS return by the 19th of each month, covering the tax month to the 5th, and pay deductions to HMRC by the 22nd (electronic).

How these dates are worked out

Three of the most important company deadlines are all measured from your accounting year-end (your accounting reference date):

Companies House accounts — due 9 months after the year-end. If your year-end is the last day of a month, the deadline is the last day of the month nine months on. For example, a 31 March year-end gives a 31 December filing deadline.
Corporation Tax payment — due 9 months and 1 day after the end of your accounting period. It's payable before the tax return that works it out is due, which catches a lot of people out.
Company Tax Return (CT600) — due 12 months after the end of your accounting period.

This calculator applies the same corresponding-date and month-end rules that Companies House and HMRC use. It's a guide, not tax advice — always check the official deadlines on GOV.UK or in your Companies House and HMRC accounts, and speak to your accountant about your specific circumstances.

Run a practice and want every one of these dates tracked for every client automatically? See how Sodium does it or get in touch.