Self Assessment Tax Return for UK Tradespeople — A Complete Guide for 2026

Who needs to file a Self Assessment tax return?

HMRC requires you to file a Self Assessment return if, in any tax year, any of the following apply to you:

• You are self-employed as a sole trader and your gross trading income exceeded £1,000 (the trading allowance threshold).
• You are a company director — even if your only income is a salary paid through PAYE.
• You have untaxed income from rental property, savings interest above your Personal Savings Allowance, or dividends above the £500 Dividend Allowance (2024/25 and 2025/26).
• Your income was over £100,000 at any point during the year.
• You received income from the Self-Employment Income Support Scheme (SEISS) grants and have not yet included them on a return.
• You want to claim certain reliefs — such as Gift Aid donations — that are not handled through PAYE.

For the vast majority of tradespeople, the sole trader threshold is the relevant trigger. If you earned more than £1,000 from any trade work in 2025/26, you need to file. That threshold has nothing to do with profit — it is gross turnover before expenses.

Key dates and deadlines for 2025/26

Missing any of these dates costs money. Mark them in your phone now.

• 5 April 2026 — End of the 2025/26 tax year. Any income earned up to this date falls within the return you will file by January 2027.
• 5 October 2026 — Deadline to register for Self Assessment if you are filing for the first time. Miss this and HMRC may charge a penalty on top of the late filing fine.
• 31 October 2026 — Deadline for paper returns for the 2025/26 tax year. Almost nobody files on paper any more, but the deadline exists.
• 31 January 2027 — Deadline for online returns and payment of any tax owed for 2025/26, plus the first payment on account toward 2026/27.
• 31 July 2027 — Second payment on account toward 2026/27.

Late filing penalties are automatic and not negotiable unless you have a reasonable excuse. The structure is: £100 immediately if you miss the 31 January deadline; £10 per day from 3 months late (up to a maximum of £900 for the daily penalty); a further penalty of 5% of the tax owed or £300 (whichever is greater) at 6 months; and another 5% or £300 at 12 months. If HMRC suspects deliberate non-compliance, penalties can reach 100% of the tax due.

What income must you include?

Your return must capture all income that was not taxed at source during the year. For tradespeople, that typically means:

• Trading income — every pound received for labour, materials, call-out charges, and any other income directly from your trade, including jobs where the customer paid cash.
• Rental income — if you let a property. The property pages of the return are separate from the self-employment pages.
• Savings interest — above your Personal Savings Allowance (£1,000 for basic rate taxpayers; £500 for higher rate; nil for additional rate).
• Dividends — if you operate through a limited company and pay yourself dividends, anything above the £500 annual Dividend Allowance must be declared.
• SEISS grant income — these grants were taxable in the year they were received. If you have any outstanding SEISS income not yet declared, include it now.
• Construction Industry Scheme (CIS) income — if you work as a subcontractor under CIS, your gross earnings go on the self-employment pages and you claim a credit for any CIS tax already deducted by the contractor.

HMRC cross-references data from banks, Checkatrade, Companies House, and increasingly from open banking feeds. Omitting cash jobs or unreported income is high-risk.

Making Tax Digital for income tax — from April 2026

Making Tax Digital (MTD) for income tax is one of the biggest changes to land on sole traders in a generation. From 6 April 2026, if your total gross income from self-employment and property exceeds £50,000 in any tax year, you must:

• Use HMRC-approved software (such as QuickBooks, Xero, FreeAgent, or one of the dedicated MTD apps) to maintain digital records of every transaction.
• Submit quarterly summary updates to HMRC — roughly in August, November, February, and May each year.
• Submit an End of Period Statement and a Final Declaration (replacing the traditional Self Assessment return) after the tax year ends.

The threshold drops to £30,000 from April 2027 and is expected to extend to all self-employed people with income above £20,000 from April 2028. Even if you are below £50,000 today, the direction of travel is clear: digital bookkeeping is becoming mandatory.

If MTD applies to you from April 2026 and you are not already using approved software, you need to act now. Non-compliance with MTD carries its own penalty regime separate from ordinary late filing penalties.

Allowable expenses for tradespeople

You can deduct any expense that is incurred "wholly and exclusively" for the purposes of your trade. For tradespeople, the list is substantial. Getting this right is where a good set of records — or a good accountant — pays for itself many times over.

Materials and stock

Any materials you purchase and use on a job — pipe, cable, plasterboard, fixings, paint — are fully deductible in the year you incur the cost. If you carry stock across year ends, only the materials actually used on jobs are deductible; unsold stock stays on the balance sheet. Keep supplier invoices for every materials purchase.

Van and vehicle costs

You have two options for claiming vehicle costs, and you must pick one method and stick with it for that vehicle:

• HMRC simplified mileage rate — 45p per mile for the first 10,000 business miles in a tax year; 25p per mile for every mile above that. This single rate covers fuel, servicing, insurance, and depreciation. You need a mileage log (date, destination, purpose, miles driven).
• Actual costs method — claim the business proportion of all real running costs: fuel, servicing, tyres, MOT, insurance, breakdown cover, road tax, and capital allowances on the purchase price. You calculate the business percentage based on business miles versus total miles driven during the year. Under this method, fuel for work journeys is included within the overall actual cost calculation.

If your van is used exclusively for work — as most trade vans are — the actual costs method typically produces a larger deduction. If you use the same vehicle privately and for work, keep a clear mileage log and apportion costs honestly.

Tools and equipment

Tools used in your trade — drills, grinders, saws, test equipment, ladders, scaffold towers — are fully deductible in the year of purchase via the Annual Investment Allowance (AIA). The AIA limit has been set at £1,000,000 per year since 2023, which is far above what most sole traders spend. In practice, everything you buy for the business gets written off immediately. Keep your receipts; HMRC can ask to see them.

Protective clothing and workwear

Specialist workwear that you cannot wear outside a work context is deductible — hi-vis jackets, steel-toe boots, hard hats, safety gloves, overalls. Ordinary clothing that you simply wear at work (jeans, a plain sweatshirt) does not qualify, even if you only wear it for work. The test is whether the item has a dual use as ordinary clothing.

Insurance

Premiums for public liability insurance, employer's liability insurance, professional indemnity, and van or tools insurance are all fully deductible business expenses. Keep your policy documents and annual invoices. Personal life insurance or income protection that is not linked to the business does not qualify.

Phone and communications

If you use one phone for both business and personal calls, you can claim the business proportion of your bill. If you have a separate business phone used exclusively for work, the entire cost is deductible. Most sole traders use a single phone; a reasonable apportionment (often 50–80% depending on usage) is accepted by HMRC if you can justify it.

Accountant fees and software subscriptions

Your accountant's fees for preparing your Self Assessment return or your accounts are deductible. So are subscriptions to bookkeeping software (QuickBooks, Xero, FreeAgent), job management software, and invoicing tools — anything used to run the business. The personal tax preparation portion of accountant fees (as opposed to the business accounts portion) can be a grey area; your accountant will advise.

Trade association memberships and training

Membership of relevant trade bodies — NICEIC, Gas Safe, NAPIT, FMB, APHC, and similar — is deductible. Training costs that maintain or update existing skills relevant to your trade are also deductible (for example, a gas engineer refreshing their ACS qualification). Training that teaches an entirely new trade or skill — moving from plastering to solar panel installation as a new business — is generally not deductible.

Working from home

If you use part of your home as an office — for quoting, invoicing, and administration — you can claim either:

• HMRC flat rate — £6 per week (£312 per year) if you work from home at least 25 hours per month. Simple, no calculation required.
• Calculated proportion — work out the business proportion of actual home costs (mortgage interest or rent, utilities, broadband) based on the number of rooms used and hours used. This often produces a larger figure but requires more paperwork.

Be cautious about claiming a room as exclusively used for business — this can create a Capital Gains Tax exposure if you ever sell the property.

Expenses you cannot claim

Knowing what you cannot claim is just as important as knowing what you can. HMRC disallows:

• Ordinary food and drink — meals and refreshments during a normal working day are not deductible. If you are working away from your base overnight, subsistence costs may be claimed, but day-to-day sandwiches are not.
• Commuting to a regular place of work — travel between your home and a fixed regular workplace (for example, a site you attend every day for months) is not deductible. Travel to different client sites typically is, because a tradesperson's workplace is itinerant.
• Ordinary clothing — as covered above, clothing that can be worn outside a work context does not qualify.
• Fines and penalties — parking fines, speeding fines, and HMRC late payment penalties are not deductible, even if incurred during work.
• Personal or private expenditure — any proportion of an expense that relates to personal use must be excluded.
• Client entertainment — taking a customer for dinner or to a sporting event is specifically disallowed under HMRC rules for sole traders.

Payments on account — how they work

If your Self Assessment tax bill exceeds £1,000, HMRC does not wait until the following January to collect all of next year's tax. Instead, it requires you to make advance payments — called payments on account — toward the following year's liability.

Each payment on account is 50% of your previous year's tax bill. You make two: the first alongside your January return, and the second the following 31 July. If your profits turn out to be lower than the previous year, you can apply to reduce your payments on account — but you must do so before the deadline, and if you reduce them too far HMRC will charge interest on the shortfall.

This catches many tradespeople off guard in their first year of trading above the threshold. You might owe, say, £3,000 in January for last year's tax plus £1,500 as the first payment on account for the current year — a total of £4,500 in a single month. Planning for this is critical. Set aside a percentage of every invoice payment (25–30% is a sensible starting point for a basic rate taxpayer) into a separate account throughout the year.

National Insurance contributions for sole traders

As a self-employed sole trader, you pay National Insurance on your profits, not on your turnover.

• Class 2 National Insurance — the flat-rate weekly contribution of £3.45 per week (2024/25 rate) was effectively abolished from April 2024. For 2024/25 onward, self-employed people with profits above the Small Profits Threshold (£6,725 for 2024/25) are treated as having paid Class 2 NI through their Self Assessment return, protecting their entitlement to State Pension without making an actual payment. Those with profits below £6,725 can make voluntary Class 2 contributions to protect their State Pension record.
• Class 4 National Insurance — charged on profits above the lower profits limit. For 2024/25, the rate is 9% on profits between £12,570 and £50,270, and 2% on profits above £50,270. Class 4 is calculated and collected through Self Assessment; you do not pay it separately.

NI rates and thresholds can change at each Autumn Statement and Spring Budget. Always check the current rates on the HMRC website or through your accountant before filing.

Keeping records — what HMRC requires

HMRC requires you to keep business records for five years from the 31 January filing deadline for that tax year. For the 2025/26 return (filed by 31 January 2027), that means keeping records until 31 January 2032.

Records you must keep include:

• Sales records — invoices raised, receipts issued, bank statements showing income received.
• Purchase records — supplier invoices, receipts for materials, tools, and all other expenses.
• Mileage log — dates, destinations, purposes, and miles for every business journey if you are claiming vehicle costs.
• Bank statements — for all business accounts and any personal accounts used for business transactions.
• CIS deduction statements — if you work under CIS as a subcontractor.
• PAYE records — if you have employees.

HMRC accepts digital records. Photographs of receipts stored in a cloud-based app are valid, provided they are legible and complete. Paper records that fade or are lost are not a reasonable excuse for an incorrect return.

Practical tips to make the return easier

• Do not wait until January. Every year, thousands of people try to file on 30 or 31 January, HMRC's online systems slow down, and last-minute panics lead to errors. Start gathering your figures in April or May once the tax year closes.
• Use accounting software throughout the year. QuickBooks, Xero, and FreeAgent all connect to your bank account and categorise transactions automatically. If MTD applies to you from April 2026, approved software is mandatory — so starting now means you are prepared and not scrambling.
• Reconcile regularly. Matching your bank statements to your invoices and receipts monthly takes 30 minutes. Doing it annually at tax time takes days and produces errors.
• Use a separate business bank account. Mixing business and personal transactions in one account is the single biggest cause of incorrect returns. A separate account makes reconciliation trivial.
• Consider a qualified accountant. For most tradespeople, a good accountant's fee is lower than the tax they save through correct deductions, and far lower than a penalty for an incorrect return. Look for an accountant who works with trades businesses and understands the sector.
• Track income by job throughout the year. When your accountant asks for your total turnover, knowing it exactly — rather than having to trawl through bank statements — saves time and money. Job management software that logs each job, invoice, and payment gives you this at a glance.
• Photograph receipts immediately. Materials receipts from builders' merchants are printed on thermal paper that fades within months. Photograph them on the day and store them digitally.

A note on IR35 and the Construction Industry Scheme

If you work through a limited company and supply your services to larger contractors or end-clients, IR35 may apply — determining whether you are taxed as an employee or as a genuine contractor. IR35 is a separate regime from Self Assessment but the two interact. Similarly, if you take on subcontractors under the Construction Industry Scheme, you have obligations as a contractor (verifying subcontractors, deducting CIS tax, filing monthly CIS returns) that sit alongside your own personal Self Assessment obligations. Both areas have specialist rules beyond the scope of this guide — speak to an accountant if either applies to you.

Summary: the numbers that matter most

• File if gross income exceeds £1,000 from self-employment.
• Online return and payment deadline: 31 January each year.
• Late filing penalty starts at £100 immediately; rises to £10/day after 3 months.
• Mileage rate: 45p/mile (first 10,000 miles); 25p/mile thereafter.
• Class 4 NI: 9% on profits £12,570–£50,270; 2% above that.
• MTD for income tax: mandatory from April 2026 if gross income exceeds £50,000.
• Keep records for 5 years after the 31 January filing deadline.
• Payments on account: 50% of last year's bill in January and July.

Self Assessment does not have to be painful. The tradespeople who find it easiest are the ones who track income and expenses consistently throughout the year — not the ones who scramble in January with a carrier bag of receipts. The discipline required is modest; the benefit at tax time is significant.