Running a small business in the UK means juggling a lot — and tax deadlines are one of the easiest things to miss. Unfortunately, HMRC penalties aren’t forgiving, even if the mistake was accidental.
This guide breaks down the key UK tax deadlines for small business owners, what each one means, and how to avoid unnecessary fines.
Self Assessment Tax Deadlines (Sole Traders & Directors)
If you’re a sole trader or a company director, you’ll usually need to submit a Self Assessment tax return.
Key dates to remember:
- 31 October – Deadline for paper tax returns
- 31 January – Deadline for online tax returns and payment of tax owed
- 31 July – Second payment on account (if applicable)
What happens if you miss it?
- £100 automatic penalty (even if no tax is owed)
- Additional daily penalties after 3 months
- Interest charged on unpaid tax
VAT Return Deadlines
If your business is VAT-registered, VAT returns are usually due quarterly.
General rule:
- VAT return and payment are due 1 month and 7 days after the end of your VAT period.
For example:
- VAT period ending 31 March → deadline is 7 May
Missing VAT deadlines can quickly lead to:
- Surcharges or penalties
- Interest on late payments
- Increased HMRC scrutiny
Corporation Tax Deadlines (Limited Companies)
If you run a limited company, Corporation Tax has two important deadlines:
- Corporation Tax payment – due 9 months and 1 day after your accounting period ends
- Company tax return (CT600) – due 12 months after your accounting period ends
Example:
- Year end: 31 March 2024
- Tax payment due: 1 January 2025
- CT600 due: 31 March 2025
PAYE & Payroll Deadlines (If You Employ Staff)
If you have employees or pay yourself via payroll:
- PAYE & National Insurance payments are due monthly (usually by the 22nd if paying electronically)
- P60s must be issued to employees by 31 May
- P11Ds (if applicable) due by 6 July
Late payroll submissions can result in:
- Fixed penalties
- Late payment interest
- Compliance checks
How to Stay on Top of Your Tax Deadlines
Many small business owners miss deadlines simply because:
- They don’t know which ones apply to them
- Dates change depending on structure (sole trader vs limited company)
- Everything feels reactive instead of planned
Using cloud accounting software, setting reminders, and working with an accountant can remove this stress completely.
FAQ: Small Business Tax Deadlines
What if I don’t earn anything this year?
You may still need to file a return — penalties apply even if no tax is owed.
Can HMRC waive penalties?
Only in limited circumstances, and it’s never guaranteed.
Do I need to file a tax return if I made no profit?
Yes. In many cases you still need to file — penalties apply even if no tax is owed.
What happens if I miss a UK tax deadline?
HMRC applies automatic penalties, interest, and in some cases further compliance action.
Can an accountant help me avoid penalties?
Yes. A good accountant ensures deadlines are met, returns are accurate, and HMRC issues are dealt with promptly.
Which tax deadlines apply to my business?
It depends on whether you’re a sole trader, limited company, VAT-registered, or an employer — many businesses have multiple deadlines.
Worried you’ve missed a deadline — or might soon?
We work with UK small business owners to manage tax deadlines, file returns correctly, and avoid HMRC penalties.