5 Tax Tips for Self-Employed Tradesmen UK [Save £1000s]

If you're a self-employed tradesman in the UK, tax is probably the last thing you want to think about. But getting it right can save you thousands of pounds a year — and keep you out of trouble with HMRC. Here are five tips that every sole trader tradesman needs to know.

1. Claim All Your Allowable Expenses

This is where most tradesmen leave money on the table. You can deduct legitimate business expenses from your income before calculating tax. The more you claim, the less tax you pay.

Common expenses tradesmen can claim:

• Tools and equipment — Drills, saws, pipe benders, testers, PPE
• Materials — Anything you buy for a job (copper pipe, cable, fixings)
• Van costs — Fuel, insurance, servicing, MOT, road tax
• Phone and internet — Business portion of your mobile bill
• Insurance — Public liability, professional indemnity, tool insurance
• Clothing — Work boots, hi-vis, branded workwear (NOT everyday clothes)
• Training and certifications — Gas Safe renewal, 18th Edition, Part P courses
• Software subscriptions — Accounting software, quoting tools (like TradeQuoteAI!)
• Accountant fees — Yes, your accountant's bill is tax-deductible

2. Understand the VAT Threshold

In 2026, you must register for VAT if your taxable turnover exceeds £90,000 in a rolling 12-month period. You can also register voluntarily below this threshold.

Should you register voluntarily?

• Yes, if most of your customers are VAT-registered businesses (they can reclaim the VAT, so it doesn't affect them)
• Yes, if you buy a lot of materials (you can reclaim VAT on purchases)
• No, if most of your work is for domestic customers (adding 20% to your prices makes you less competitive)

If you're near the threshold, speak to an accountant. Getting caught unregistered when you should be can mean backdated VAT bills and penalties.

3. Set Aside Money for Tax

The biggest mistake self-employed tradesmen make is spending everything they earn and then panicking when the tax bill arrives in January.

Rule of thumb: Put aside 25-30% of your profit into a separate savings account every month. This covers:

• Income Tax (20% on earnings above £12,570)
• National Insurance Class 2 (£3.45/week) and Class 4 (6% on profits £12,570-£50,270)

Set up a standing order on payday and forget about it. When January comes, the money is there waiting.

4. Know Your Key Deadlines

Miss a deadline and HMRC will hit you with automatic penalties. Here are the dates you need in your calendar:

• 5 October — Register for Self Assessment (if you're newly self-employed)
• 31 October — Paper tax return deadline
• 31 January — Online tax return AND payment deadline for the previous tax year
• 31 July — Second payment on account (if applicable)

Late filing penalty: £100 immediately, rising to £10/day after 3 months. Late payment: interest + 5% surcharge. It's not worth it.

5. Keep Proper Records

HMRC requires you to keep records of all income and expenses for at least 6 years. This includes:

• All invoices you've sent
• All receipts for expenses
• Bank statements
• Mileage logs (if claiming vehicle expenses)

Digital records are perfectly acceptable — and much easier to manage. Using proper invoicing and quoting software means your records are already organised when tax time comes around.

Bonus: The Trading Allowance

If your total self-employed income is under £1,000 in a tax year, you don't need to report it to HMRC. This is useful for tradesmen who do occasional side jobs while employed full-time.

Understand Payments on Account

Once your tax bill is over a certain level, HMRC asks you to pay towards next year's bill in advance, in two payments on account due by 31 January and 31 July. In the first year this applies, it can feel like paying one and a half years of tax at once. Setting aside a fixed percentage of every payment you receive makes these dates far less painful.

Making Tax Digital for Income Tax

HMRC is phasing in Making Tax Digital for Income Tax, which requires self-employed people above certain income levels to keep digital records and send quarterly updates using compatible software. It starts from April 2026 for those with qualifying income over £50,000, with lower thresholds following in later years. Check GOV.UK to see when it applies to you, and move your records into software early rather than at the last minute.

Working in Construction? Understand CIS

If you work as a subcontractor for building contractors, you may be paid under the Construction Industry Scheme (CIS), where the contractor deducts money from your payments and passes it to HMRC. Registered subcontractors usually have 20% deducted, and unregistered subcontractors 30%. These deductions count towards your tax bill, so keep every CIS statement — they can reduce what you owe or lead to a refund.

National Insurance

Since April 2024, self-employed people no longer have to pay Class 2 National Insurance, but Class 4 National Insurance is still charged on profits above a set threshold, and is paid through your Self Assessment. Rates and thresholds change, so check the current figures on GOV.UK when you work out how much to set aside.

When to Get an Accountant

Plenty of sole traders do their own tax return, but an accountant often pays for themselves once your business grows, you take on staff, register for VAT, or start thinking about becoming a limited company. At the very least, a one-off review of your expenses can uncover allowable costs you've been missing.