What Can I Claim on My Self Assessment Tax Return?

On your UK Self Assessment tax return you can claim the business costs you incurred wholly and exclusively to run your trade — office supplies, travel, business premises, stock, staff wages, insurance, marketing, professional fees, and finance costs — along with a deduction for working from home, capital allowances on equipment, and personal reliefs such as pension contributions and Gift Aid donations. Everything below unpacks how each of those works, what the limits are, and where each figure goes on the form.

The Wholly and Exclusively Test

Every expense claim starts with one question: was the cost incurred wholly and exclusively for business purposes? Section 34 of the Income Tax (Trading and Other Income) Act 2005 sets this out.¹ If a cost has a dual personal and business purpose, you cannot claim the full amount.

Where an asset is used partly for business and partly for personal life, you deduct only the business portion. A laptop used 70% for client work and 30% for personal browsing means you claim 70% of the cost. The same logic applies to phone bills, broadband, and household utilities when you work from home. This proportional approach runs through almost every category below.

The £1,000 Trading Allowance

Before you start tallying receipts, check whether the trading allowance is the simpler route. If your total self-employment income is £1,000 or less in the tax year, it’s tax-free and you don’t need to report it. If your income exceeds £1,000, you can still deduct a flat £1,000 instead of claiming actual expenses, but not both. Once you use the trading allowance, no other expense deductions or capital allowances are available against that income.²

For most people earning well above £1,000, actual expenses will produce a bigger deduction. If your costs are minimal, the flat allowance saves you from keeping detailed records.

Business Expenses You Can Claim

These are the categories most sole traders encounter. Each maps to a box on the SA103 supplementary pages filed alongside your main SA100 return.³

Office costs: stationery, printer ink, phone bills, postage, and computer software.
Business premises: rent, business rates, water, electricity, and gas for your workspace. If you work from home, only the business proportion qualifies.
Travel: fuel for business trips, train and bus fares, parking, and road tolls when visiting clients or suppliers. Commuting between your home and a regular workplace does not count.
Stock and materials: anything you buy to resell or to manufacture products.
Staff costs: wages, salaries, subcontractor fees, and employer National Insurance contributions.
Insurance: public liability, professional indemnity, and other policies covering business risks.
Repairs and maintenance: fixing or maintaining business property and equipment. Improvements that add value rather than restore it are treated as capital expenditure instead.
Marketing and advertising: website hosting, business cards, online advertising, and promotional materials.
Financial costs: interest on business loans or credit cards used for trade purposes, and charges on a dedicated business bank account.
Professional fees: payments to accountants, solicitors, or surveyors for business-specific work. The cost of preparing your business accounts is deductible; drafting a personal will is not.

The SA103S short form uses boxes 11 through 19 for these categories, with box 20 as the total.⁴ If your turnover exceeds the VAT threshold, you’ll use the longer SA103F form, which has additional boxes.⁵

What You Cannot Claim

Client entertaining is explicitly excluded. No claiming meals or hospitality for customers, however productive the dinner was. The SA103S form itself states that client entertaining costs are not allowable.⁴ Fines and penalties, including parking tickets and HMRC late payment charges, are not deductible. Neither is personal spending, even if it happens during the working day.

Working From Home

Two approaches are open to you. The first is to calculate the actual proportion of household costs attributable to your workspace, dividing bills like electricity, heating, broadband, and council tax by the fraction of rooms or floor area used for work. This can produce a larger deduction but requires careful record-keeping.

The second uses HMRC’s simplified flat rates, based on hours worked from home each month:⁶

25 to 50 hours per month: £10
51 to 100 hours per month: £18
101 or more hours per month: £26

You must work at least 25 hours a month from home to use these rates. They cover utilities and general household running costs without requiring you to apportion individual bills, though you still need a log of hours worked. For someone working full-time from a home office, actual costs will often beat the flat rate. £26 per month is only £312 for the year, likely less than a realistic proportion of your heating, electricity, and broadband bills.

Vehicle Mileage

Instead of tracking petrol receipts, insurance, servicing, and depreciation, you can claim a flat rate per business mile:⁷

First 10,000 business miles: 45p per mile
Each mile above 10,000: 25p per mile

If you choose the flat rate, you cannot also claim actual vehicle running costs. Whichever method you pick, stick with it for that vehicle. You can’t switch methods for the same car partway through. Keep a mileage log recording each business trip: date, destination, purpose, and distance.

Sole traders who live at their business premises, a common setup for guesthouse or B&B owners, can also use a flat monthly amount for personal use of the space, with the amount varying by how many people live there.⁷

Capital Allowances for Equipment

Day-to-day expenses like stationery and travel are deducted in the year you spend the money. When you buy something that lasts, such as a van, machinery, or a computer, the cost is handled through capital allowances rather than ordinary expenses.⁸

The Annual Investment Allowance (AIA) lets you deduct the full cost of qualifying plant and machinery up to £1,000,000 per year.⁹ For most sole traders this means 100% tax relief on equipment purchases in the year you buy them. Qualifying items include tools, machinery, business vehicles such as vans, computers, and office furniture.

If spending exceeds the AIA, or you have assets that don’t qualify, the remaining cost goes into a writing down allowance pool. You deduct 18% of the pool value each year for most plant and machinery, or 6% for items in the special rate pool (integral building features, long-life assets, and higher-emission cars).¹⁰

Capital allowances cannot be claimed for stock-in-trade (goods you buy and sell), day-to-day running costs, or interest on loans used to buy assets.⁸ Those belong in the ordinary expense categories.

Clothing and Training

You can claim for uniforms, protective clothing required for your work, and costumes if you’re an actor or entertainer. Everyday clothing is never deductible, even if you wear it exclusively for work. A plumber’s steel-toe boots qualify; a consultant’s suit does not.¹¹

Training costs are deductible when they improve skills you already use in your business, keep you current with industry technology, or develop new skills related to changes in your sector. Administrative training, such as a bookkeeping course for managing your own accounts, also counts.¹² What you cannot claim is training to start an entirely new business or to expand into unrelated areas. A web designer paying for an advanced JavaScript course can claim it. The same web designer paying for a property investment seminar cannot.

Pre-Trading Expenses

Money spent setting up your business before you officially started trading can still be claimed. Qualifying expenses incurred up to seven years before your start date are treated as though spent on day one of trading.¹³

The expense must be something that would have been deductible had you already been trading when you incurred it. The same wholly and exclusively test applies. A laptop bought six months before launch for the purpose of the business qualifies. A holiday that inspired you to change careers does not. These costs are added to your expenses in your first trading period.

Pension Contributions and Gift Aid

These are personal reliefs rather than business expenses, and they go on the main SA100 form, not the self-employment pages.

Pension Contributions

Most pension providers operate on a relief at source basis, meaning they automatically claim basic rate (20%) tax relief from HMRC and add it to your pot. If you’re a basic rate taxpayer, there’s nothing more to do.¹⁴

Higher and additional rate taxpayers claim the extra relief through Self Assessment. A 40% taxpayer can reclaim an additional 20% on contributions; a 45% taxpayer can reclaim an additional 25%. Enter your gross pension contributions (including the basic rate top-up) in the Tax reliefs section of the SA100. HMRC either reduces your tax bill or adjusts your tax code. You can claim relief on contributions up to 100% of your annual earnings.

Gift Aid Donations

Charitable donations through Gift Aid also generate tax relief for higher rate taxpayers. The charity claims 25% on top of your donation at the basic rate, and you claim back the difference between your tax rate and the basic rate through Self Assessment. Reporting Gift Aid donations extends your basic rate band, so more of your income is taxed at 20% rather than 40% or 45%.¹⁵

There is a cap. Your total Gift Aid donations in a tax year must not exceed four times the total Income Tax and Capital Gains Tax you’ve paid that year. If you over-claim, HMRC can claw back the difference.

Records and Where Each Claim Goes

Keep invoices, receipts, bank statements, and mileage logs for every expense you plan to deduct. HMRC requires you to retain these records for at least five years from 31 January following the tax year the return covers. For the 2025/26 tax year, filed by January 2027, records must be kept until at least 31 January 2032.

Self-employment income and expenses go on the SA103 supplementary pages. Below the VAT threshold, the short version (SA103S) is sufficient.³ Above the VAT threshold, use the full version (SA103F).⁵ Pension contributions and Gift Aid go on the main SA100.¹⁶ The deadline for online filing is 31 January following the end of the tax year, with paper returns due by 31 October.¹⁷

1
Legislation.gov.uk. United Kingdom Code 2005 c. 5 – Income Tax (Trading and Other Income) Act 2005
2
GOV.UK. Tax-free Allowances on Property and Trading Income
3
GOV.UK. Self Assessment: Self-employment (short) (SA103S)
4
HM Revenue & Customs. SA103S 2025 Self-employment (short)
5
HM Revenue & Customs. Self Assessment: Self-employment (full) (SA103F)
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GOV.UK. Simplified Expenses if You’re Self-Employed: Working from Home
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GOV.UK. Simplified Expenses if You’re Self-Employed
8
GOV.UK. Claim Capital Allowances
9
GOV.UK. Claim Capital Allowances: Annual Investment Allowance
10
GOV.UK. Work Out Your Writing Down Allowances: Rates and Pools
11
GOV.UK. Expenses if You’re Self-Employed: Clothing Expenses
12
GOV.UK. Expenses if You’re Self-Employed: Training Courses
13
Legislation.gov.uk. United Kingdom Code 2005 c. 5 – Income Tax (Trading and Other Income) Act 2005 – Section 57
14
GOV.UK. Tax on Your Private Pension Contributions: Pension Tax Relief
15
GOV.UK. Tax Relief When You Donate to a Charity: Gift Aid
16
GOV.UK. Self Assessment Tax Return Forms
17
GOV.UK. Self Assessment Tax Returns: Deadlines