End of Tax Year Checklist for UK Trades (31 March 2026)
The Reality:
31 March isn't just a date. It's the tax year deadline that triggers self-assessment, VAT returns, CIS deductions, and limited company accounts. Miss a deadline and penalties start at £100, climbing to £1,000+ for persistent delays. Here's everything you need to file on time.
Keep the rest of your compliance stack tight with Complete CIS Tax Guide for Subcontractors 2026, UK Trades Tax Deduction Checklist, and Sole Trader vs Limited Company for Trades.
The UK tax year runs 6 April to 5 April. But the serious deadlines cluster around 31 March (company accounts) and 31 January (self-assessment payment). This checklist covers what you need to do between now and April to stay HMRC-compliant and avoid penalties.
⚠️ Not Tax or Accounting Advice
This guide is for informational purposes only and does not constitute tax advice, accounting advice, or professional financial services. Tax laws, allowances, and HMRC requirements change frequently.
Before making any tax decisions or filing returns: Consult a qualified accountant or tax advisor who can review your specific circumstances. What's mentioned here may not apply to your situation, and regulations may have changed since publication.
Official source: HMRC (gov.uk/hmrc)
Critical Dates: Tax Year 2025/26
These are the non-negotiable deadlines. Miss them and HMRC penalties start immediately.
| Date | Deadline | Penalty if Late |
|---|---|---|
| 5 April 2026 | Tax year ends. All income/expenses for 2025/26 tax year finalized | - |
| 19 April 2026 | Final CIS return for March 2026 (tax month ending 5 April) | £100 immediate penalty |
| 30 April 2026 | Final VAT return for quarter ending 31 March (if quarterly filing) | £100 + daily penalties after 2 months |
| 31 July 2026 | Second payment on account for 2025/26 tax year (sole traders) | Interest charges on late payment |
| 31 December 2026 | Limited company accounts filed at Companies House (if year-end 31 March 2026) | £150-£1,500 depending on delay |
| 31 January 2027 | Self-assessment tax return filed + final payment for 2025/26 | £100 + £10/day after 3 months |
Sole Trader End-of-Year Checklist
If you're self-employed as a sole trader, here's what you need to gather before your accountant can file your tax return.
Income Records to Gather
What You Need:
- ☐ Total invoiced income: All invoices issued 6 April 2025 - 5 April 2026
- ☐ Cash/card payments received: Full bank statements showing deposits
- ☐ CIS deductions: CIS payment/deduction statements from contractors (if subcontractor)
- ☐ Other income: Interest, dividends, rental income (if applicable)
Expense Records to Gather
These reduce your taxable profit. The more legitimate expenses you claim, the less tax you pay.
Vehicle Expenses
- ☐ Business mileage log (total miles, business vs personal split)
- ☐ Van/car purchase receipts (for capital allowances)
- ☐ Fuel receipts (if claiming actual costs vs mileage rate)
- ☐ Insurance, tax, MOT, servicing receipts
- ☐ Parking, tolls, congestion charge receipts
Tools, Materials & Equipment
- ☐ Tool purchase receipts (hand tools, power tools)
- ☐ Materials bought for jobs (timber, fittings, paint, etc.)
- ☐ Safety equipment (boots, hi-vis, hard hat, gloves)
- ☐ Specialist equipment (testing gear, ladders, scaffolding)
Office & Admin
- ☐ Home office expenses (flat rate £26/month OR actual running cost %)
- ☐ Phone/broadband bills (business portion)
- ☐ Software subscriptions (Toolfy, accounting software, etc.)
- ☐ Stationery, printing, postage
- ☐ Bank charges on business account
Professional Fees & Insurance
- ☐ Accountant fees
- ☐ Public liability insurance
- ☐ Professional indemnity insurance
- ☐ Tool insurance
- ☐ Trade association memberships (NICEIC, Gas Safe, etc.)
Training & Marketing
- ☐ Course fees (CPD, certifications, renewals)
- ☐ Website hosting/design
- ☐ Advertising (Google Ads, Facebook, local directories)
- ☐ Uniforms with business logo
- ☐ Business cards, flyers, van signage
Records You Must Keep (6 Years)
HMRC requires you to keep records for at least 5 years after the 31 January submission deadline (effectively 6 years total). Keep these:
- All invoices issued
- All receipts for expenses claimed
- Bank statements showing business income/expenses
- Mileage logs
- VAT records (if VAT registered)
- CIS deduction statements
Limited Company End-of-Year Checklist
If you operate as a limited company, your responsibilities are different (and more complex).
Company Accounts Preparation
What Your Accountant Needs:
- ☐ Full bank statements for all business accounts (entire financial year)
- ☐ All sales invoices issued
- ☐ All purchase invoices/receipts
- ☐ Payroll records (if you have employees or take salary as director)
- ☐ Dividend vouchers (if you paid yourself dividends)
- ☐ Loan agreements (if company lent/borrowed money)
- ☐ Asset purchase records (vehicles, equipment over £500)
Limited Company Filing Deadlines
Limited companies have two separate filings with different deadlines:
| Filing | Deadline | Where |
|---|---|---|
| Annual accounts | 9 months after year-end (31 Dec 2026 if year-end 31 March 2026) | Companies House |
| Corporation Tax return | 12 months after year-end (31 March 2027 if year-end 31 March 2026) | HMRC |
| Corporation Tax payment | 9 months + 1 day after year-end (1 Jan 2027 if year-end 31 March 2026) | HMRC |
| Confirmation statement | Annual (exact date depends on company registration date) | Companies House |
VAT & CIS Final Returns
VAT Quarter Ending 31 March 2026
If you're VAT registered and file quarterly, your final return for the tax year covers 1 January - 31 March 2026.
VAT Return Checklist:
- ☐ Sales (output VAT): All VAT charged on invoices issued Jan-March
- ☐ Purchases (input VAT): All VAT paid on expenses Jan-March
- ☐ Calculate net VAT: Output VAT - Input VAT = amount owed/refund due
- ☐ File by 7 May 2026: Online submission via MTD software
- ☐ Pay by 7 May 2026: Direct debit or bank transfer to HMRC
CIS Monthly Return (Final for Tax Year)
If you pay subcontractors, your final CIS return for the tax year covers 6 March - 5 April 2026 (tax month 12).
- File by 19 April 2026
- Include all subcontractor payments made in that period
- Report CIS deductions taken (20%, 30%, or 0% depending on subcontractor status)
- Pay deductions to HMRC by 22 April 2026 (electronic payment)
Common End-of-Year Mistakes
Expensive Mistakes to Avoid:
- 1. Missing the self-assessment deadline (31 Jan): £100 immediate penalty + £10/day after 3 months
- 2. Not claiming all allowable expenses: Average £3,000-£5,000 left unclaimed = £600-£1,000 extra tax
- 3. Forgetting CIS deductions on tax return: You won't get credit for tax already paid via CIS
- 4. Using personal expenses as business expenses: HMRC audit red flag, penalties + interest if caught
- 5. Late company accounts filing: £150 penalty (1 month late), £375 (3 months), £750 (6 months), £1,500 (12 months)
Preparing for Your Accountant
Most accountants charge £400-£800 for year-end accounts. You can reduce this (and get faster service) by being organized.
The Accountant-Ready Pack
What to Send Your Accountant (Before 31 December):
- ☐ Profit & loss report (income - expenses) for full tax year
- ☐ Bank statements (all business accounts, full year)
- ☐ Invoice summary (total invoiced income)
- ☐ Expense summary by category (spreadsheet or software export)
- ☐ VAT returns (if applicable)
- ☐ CIS deduction statements (if subcontractor)
- ☐ Payroll records (if employees or director salary)
- ☐ Any changes to business (new equipment, loans, etc.)
Questions Your Accountant Will Ask
Be ready to answer these:
- "Did you work from home? How many hours per week?" (home office allowance)
- "What percentage of your vehicle use was business vs personal?" (vehicle expense split)
- "Did you buy any equipment over £500?" (capital allowances)
- "Are there any bad debts you won't recover?" (write-offs)
- "Did you take any dividends or director salary?" (limited company only)
What Happens in April (New Tax Year)
6 April 2026 starts the 2026/27 tax year. Here's what kicks off:
New Tax Year Admin (April 2026):
- ☐ First payment on account due 31 Jan 2027: If self-employed, set aside 50% of estimated tax bill
- ☐ New CIS year starts: Month 1 return due 19 May 2026
- ☐ New VAT quarter starts: Q1 return (Apr-Jun) due 7 August 2026
- ☐ Review allowances: Annual Investment Allowance limit, mileage rates (check HMRC for 2026/27 updates)
- ☐ Update software: Ensure accounting/invoicing software reflects new tax year
The Bottom Line
End of tax year isn't one deadline—it's a cascade of deadlines from April through January. Miss one and the penalties compound.
Your End-of-Year Timeline:
Now - 31 March:
Gather all income/expense records, chase outstanding invoices, finalize purchases
April:
File final VAT/CIS returns, send records to accountant
May - December:
Accountant prepares accounts, file company accounts (if limited), pay Corporation Tax
31 January 2027:
Self-assessment filed + final payment for 2025/26 + first payment on account for 2026/27
Start now. Gather receipts today. Send to accountant by December. File by January. Avoid penalties.
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See Toolfy's year-end reports →Related Articles
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