UK Small Business Tax Deadlines & Compliance Guide 2026/27

Written by Calvin Lo, Founder of Aphelios Software | July 2026 | 8 min read

Keeping up with UK tax deadlines is one of the most important responsibilities for any small business owner. Missing a deadline can mean automatic penalties, interest charges, and unnecessary stress.

This guide covers all the key HMRC deadlines for 2026/27 including Self Assessment, VAT, Making Tax Digital, Corporation Tax, PAYE, and practical tips for staying compliant throughout the year.

1. Self Assessment Tax Return Deadlines 2026/27

If you are self-employed, a sole trader, or a partner in a business partnership, you must file a Self Assessment tax return each year.

• Paper tax return deadline: 31 October 2026 (for 2025/26 tax year)
• Online tax return deadline: 31 January 2027
• Payment deadline: 31 January 2027
• Second payment on account deadline: 31 July 2027

Late filing incurs an automatic £100 penalty, with additional daily penalties if you are more than 3 months late. Interest also accrues on late payments.

2. VAT Return Deadlines 2026/27

Businesses with a VAT-registered turnover above £90,000 must submit VAT returns and make payments to HMRC. VAT returns are typically due one calendar month and 7 days after the end of your accounting period.

• Quarterly VAT returns: Due 1 month and 7 days after quarter end
• Monthly VAT returns: Due 1 month and 7 days after month end
• Annual Accounting Scheme: One return per year with interim payments

All VAT-registered businesses must use Making Tax Digital (MTD) compatible software to submit returns digitally. Spreadsheets are permitted when used with bridging software.

3. Making Tax Digital (MTD) for Income Tax

HMRC's Making Tax Digital initiative is phasing in for Income Tax Self Assessment.

• From April 2026: Self-employed individuals and landlords with gross income over £50,000 must follow MTD rules
• From April 2027: Threshold drops to £30,000
• Requirements: Digital record keeping, quarterly updates to HMRC, final declaration at year end

Using inventory and accounting software that integrates with HMRC's systems makes MTD compliance straightforward. Read our guide on Making Tax Digital and inventory software for more details.

4. Corporation Tax Deadlines

Limited companies must pay Corporation Tax on their profits and file a Company Tax Return.

• Payment deadline: 9 months and 1 day after the end of your accounting period
• Company Tax Return filing deadline: 12 months after the end of your accounting period

Corporation Tax is now set at 25% for profits over £250,000, with a small profits rate of 19% for profits under £50,000. Marginal relief applies between these thresholds.

5. PAYE and Payroll Deadlines

If you employ staff, you must operate PAYE (Pay As You Earn) and report payroll information to HMRC on or before each pay day.

• RTI submission: On or before each pay day
• PAYE payment deadline: 22nd of the following month (19th if paying by post)
• P60 deadline: 31 May 2027 (give to employees)
• P11D deadline: 6 July 2027 (file and give to employees)

6. Other Key Deadlines

• Capital Gains Tax on property: Report and pay within 60 days of completion
• Construction Industry Scheme (CIS): Monthly returns by the 14th of each month
• Annual accounts to Companies House: 9 months after accounting period end (private limited companies)
• Confirmation Statement: Annual update to Companies House

2026/27 Tax Calendar at a Glance

How Software Helps with Tax Compliance

Using integrated business software can simplify tax compliance significantly. Features that help include:

• Real-time sales and transaction records for accurate VAT returns
• Automated digital records for MTD compliance
• Purchase order and expense tracking for Corporation Tax calculations
• Barcode scanning for accurate stock valuation
• Integrated reporting for profit and loss visibility

Aphelios Software provides inventory management, POS, invoicing, and CRM features that maintain accurate digital records, making tax time less stressful and more efficient.