UK Tax Deadlines 2026/27: The Complete Calendar for Small Businesses

TL;DR: Key UK Tax Deadlines 2026/27

Introduction to UK Tax Deadlines

Navigating the labyrinth of UK tax deadlines can be a daunting task for any small business owner. Missing a deadline, even by a day, can result in penalties and unnecessary stress. This comprehensive guide provides a clear, month-by-month calendar of all essential UK tax deadlines for the 2026/27 tax year, ensuring you stay compliant and avoid common pitfalls. We'll cover Self Assessment, Corporation Tax, VAT, PAYE, P60, P11D, CIS, and Companies House requirements, along with practical advice on setting up reminders.

The UK Tax Year 2026/27: Key Dates

The UK tax year runs from 6 April to 5 April the following year. The 2026/27 tax year commenced on 6 April 2025 and concludes on 5 April 2026. Most deadlines for this tax year will fall in late 2026 and early 2027.

Self Assessment Deadlines 2026/27

Self Assessment is the system HMRC uses to collect Income Tax. If you're self-employed, a sole trader, or receive untaxed income, you'll likely need to complete a Self Assessment tax return.

Corporation Tax Deadlines 2026/27

Limited companies pay Corporation Tax on their profits. Unlike Self Assessment, Corporation Tax deadlines are tied to your company's accounting period, not the standard tax year.

VAT Return Deadlines 2026/27

If your business is VAT registered, you'll need to submit regular VAT returns and make payments to HMRC. The frequency (monthly, quarterly, or annually) depends on your business's turnover and scheme.

PAYE Deadlines 2026/27

If you employ staff, you operate PAYE (Pay As You Earn) to deduct Income Tax and National Insurance from their wages. These deductions must be paid to HMRC monthly or quarterly.

Other Important Deadlines

• P60s: Employers must provide P60s to employees by 31 May 2026.
• P11D/P11D(b): Forms for reporting expenses and benefits must be submitted to HMRC by 6 July 2026. Employees should also receive a copy by this date.
• CIS Returns: Contractors must submit monthly CIS (Construction Industry Scheme) returns by the 19th of each month for the previous tax month.
• Companies House Confirmation Statement: This must be filed at least once every 12 months. The deadline is usually 14 days after the anniversary of your company's incorporation or the date you filed your last confirmation statement.

Penalties for Missing Deadlines

HMRC imposes penalties for late filing and late payment across all tax regimes. These can quickly add up, so it's crucial to be aware of them.

Self Assessment Penalties

• Late Filing:
  • 1 day late: Automatic £100 penalty.
  • 3 months late: Additional £10 daily penalties for up to 90 days (max £900).
  • 6 months late: Further penalty of 5% of the tax due or £300, whichever is greater.
  • 12 months late: Another 5% of the tax due or £300, whichever is greater.
• Late Payment:
  • 30 days late: 5% of the tax unpaid.
  • 6 months late: Another 5% of the tax unpaid.
  • 12 months late: Another 5% of the tax unpaid.

Corporation Tax Penalties

• Late Filing of Company Tax Return (CT600):
  • 1 day late: £100 penalty.
  • 3 months late: Another £100 penalty.
  • 6 months late: HMRC will estimate your Corporation Tax bill and add a penalty of 10% of the unpaid tax.
  • 12 months late: Another 10% of any unpaid tax.
• Late Payment of Corporation Tax:
  • Interest is charged on overdue amounts.
  • Penalties can also be applied for serious delays or repeated failures.

VAT Penalties

HMRC operates a penalty points system for late VAT returns. You get a point each time you miss a deadline. Once you reach a certain points threshold, you'll receive a £200 penalty. A further £200 penalty is issued for each subsequent late submission while at or above the threshold.

• Late Submission: Penalty points system leading to £200 penalties.
• Late Payment: Interest is charged, and a late payment penalty may apply, starting at 2% of the outstanding VAT after 15 days, increasing to 4% after 30 days, and further penalties for longer delays.

How to Set Up Reminders in Accounting Software

Modern accounting software is your best friend when it comes to managing tax deadlines. Most popular platforms offer robust reminder systems and integrations with HMRC.

1. Integrate with HMRC: Ensure your accounting software is MTD-compliant and linked directly to your HMRC online account. This allows for seamless submission of VAT returns and often provides real-time updates on your tax position.
2. Automate Reminders: Configure your software to send automated email or in-app notifications for upcoming deadlines. This includes VAT, PAYE, and Corporation Tax. For Self Assessment, you might need to manually add these to your personal calendar, though some software offers integrations.
3. Utilise Reporting Features: Regularly run reports on your tax liabilities within your software. This helps you anticipate upcoming payments and manage your cash flow effectively.
4. Consult Your Accountant: If you use an accountant, ensure they have access to your accounting software. They can often manage submissions and deadlines on your behalf, providing an extra layer of security.

Conclusion

Staying on top of UK tax deadlines is fundamental to the smooth operation and financial health of your small business. By understanding the key dates for Self Assessment, Corporation Tax, VAT, and PAYE, and by leveraging the power of modern accounting software, you can avoid penalties and focus on what you do best - growing your business. Remember, proactive planning and timely action are your greatest assets in tax compliance.