Side hustle tax expenses: what you can (and can't) deduct (UK 2025/26)

Direct answer in 60 words

Yes, UK side-hustle expenses are tax-deductible if they are wholly and exclusively for the trade. Common allowable categories are home-office (flat-rate or apportioned bills), business-use phone and broadband, mileage, equipment, software, marketing, professional fees, and training that maintains existing skills. As an alternative to listing real costs, you can deduct the flat £1,000 trading allowance — pick whichever is bigger.

The two routes: trading allowance vs actual expenses

For each side-hustle trade in each tax year you choose one route to reduce your taxable profit:

• £1,000 trading allowance — a flat deduction against gross trading income, no records of costs needed. It cannot create a loss, and it cannot be combined with actual expenses for the same trade. Full mechanics in how much tax do you pay on the trading allowance.
• Actual allowable expenses — the real running costs of the side hustle, kept on file with receipts/invoices. Can produce a loss that you can carry forward (or, in some cases, sideways).

Rule of thumb: if your annual expenses are above £1,000, claim actuals; below £1,000, the allowance usually wins.

Worked example — £4,000 income, £900 expenses

You earn £4,000 from a freelance side hustle and spend £900 on software, a domain, marketing and a small bit of equipment.

• Allowance route: £4,000 − £1,000 = £3,000 taxable profit.
• Actuals route: £4,000 − £900 = £3,100 taxable profit.
• Allowance wins by £100 of profit — about £20 of tax at the basic rate, £40 at the higher rate.

Once your real costs cross £1,000, the actuals route always wins. Run both numbers in the calculator above by typing £1,000 in the expenses field and then your real total — pick whichever gives the lower Income Tax + Class 4 NI.

The "wholly and exclusively" rule, in plain English

HMRC's core test for any expense is whether it was incurred wholly and exclusively for the purposes of the trade. A cost with a real personal benefit usually fails the test outright — the famous Mallalieu v Drummond case denied a barrister tax relief on her black court clothes because they also kept her warm and decent in public. Mixed-use costs where the business and personal portions are clearly separable (a phone bill, a car) are split by a fair apportionment instead of being disallowed entirely.

Allowable expense categories with UK examples

1. Home office — the simplified flat rate

If you work from home for at least 25 hours a month on the side hustle, HMRC's simplified expenses let you skip the apportioned-bills calculation and claim a flat monthly amount instead:

• £10/month for 25–50 hours of business use
• £18/month for 51–100 hours
• £26/month for 101+ hours

That covers heat, light and power. Broadband and phone are not in the flat rate and are claimed separately on the business-use percentage. The alternative — apportioning real household bills (electricity, gas, council tax, rent or mortgage interest, water, insurance, repairs) by the floor area and time used — sometimes pays better, but the record-keeping load is much higher.

2. Phone and internet

Claim the business-use percentage of your monthly bill. A reasonable estimate based on usage is acceptable — for example, an itemised review showing 40% of calls were business gives you 40% of the line rental and call charges. If you have a separate phone or SIM used only for the side hustle, the whole cost is deductible.

3. Travel and mileage

Business journeys count; ordinary home-to-work commuting does not. Two options for cars/vans:

• Simplified mileage: 45p per mile for the first 10,000 business miles in the tax year, 25p per mile after that. Motorcycles are 24p flat. Bicycles 20p. The simplest option for low-volume drivers.
• Actual costs: a business-use percentage of fuel, insurance, servicing, MOT, breakdown cover and capital allowances on the vehicle itself. Lots more paperwork; usually worth it for higher-mileage trades.

You must pick one method per vehicle and stick with it for as long as you own that vehicle. Public transport, taxis, parking and toll fees for business trips are claimed at actual cost.

4. Equipment, software and consumables

Day-to-day consumables (printer ink, packaging, postage, stationery) are revenue expenses and deducted in the year you buy them. Tools and equipment with a useful life of more than one tax year (laptop, camera, sewing machine, power tools) are capital items — see capital allowances below. Subscription software (Adobe Creative Cloud, accounting tools, hosting, email, design assets) is a normal revenue expense.

5. Marketing and websites

Domain registration, hosting, SaaS tools, paid ads (Google, Meta, TikTok), printed leaflets, business cards and email marketing platforms are all allowable. The build cost of a brand-new website is a grey area — small, regularly updated marketing sites are usually accepted as revenue, while a major bespoke build with long-term value can be capital.

6. Professional fees and insurance

Allowable: accountant's fees for preparing your accounts and Self Assessment, bookkeeping software, professional indemnity insurance, public liability insurance, trade body memberships relevant to the business. Not allowable: fines, parking penalties, the cost of disputing a personal tax bill, or premiums for personal life or critical illness cover.

7. Training (the duality-of-purpose trap)

Training is allowable when it maintains or updates skills you already use in the trade. It is not allowable when it gives you new skills that expand the business in a fundamentally different direction — HMRC treats that as capital. A freelance copywriter taking an SEO course = deductible. The same copywriter taking a beginner-level coding bootcamp to pivot into web development = capital, not deductible against current trading profit.

Capital allowances vs revenue expenses

Anything with a useful life longer than one tax year is capital. Instead of being deducted in the year you buy it, it is claimed under capital allowances:

• Annual Investment Allowance (AIA): a 100% deduction in the year of purchase, up to £1,000,000 of qualifying plant and machinery (laptops, cameras, tools, equipment). Almost every side hustle's capital spending fits comfortably inside the AIA.
• First Year Allowance (FYA): 100% relief for specific items such as new and unused zero-emission cars and certain energy-efficient equipment.
• Writing Down Allowances: for items not covered by AIA/FYA, you spread the deduction over several years at 18% (main pool) or 6% (special rate pool, including most cars).

Important: capital allowances are only available on the actuals route. If you claim the £1,000 trading allowance you cannot also claim AIA or any other capital allowance for that trade. Full HMRC detail is on the GOV.UK capital allowances guide.

The mistakes that get claims rejected

1. Everyday clothing. Smart shirts, suits, "work outfits", and content-creator wardrobes are out. Only protective gear and branded uniforms qualify.
2. Meals and food. Lunch on a normal working day is not deductible — you have to eat anyway. Subsistence on overnight business trips and reasonable meals on genuinely irregular travel are usually allowed; client entertaining is not.
3. Mixing the trading allowance and expenses. It is one or the other per trade per year. Pick the bigger deduction.
4. Treating the home office as a separate room with no personal use. Doing this can trigger a slice of capital gains tax when you sell your home. Almost all side-hustlers should use the simplified flat rate or an apportioned share of bills, not designate a dedicated business-only room.
5. Forgetting to apportion mixed-use costs. A phone, broadband line, car or home that you also use personally must be split — claiming 100% of the cost is the single most common reason an enquiry escalates.
6. Capital items deducted as revenue. A £900 laptop is capital, not stationery. Claim it under AIA, not as a one-line "computer" expense in the wrong category.
7. Pre-trade expenses missed entirely. Costs incurred in the seven years before you started trading (hosting, domain, equipment) can be brought into the first year's accounts as if incurred on day one. Many side-hustlers forget this.

Putting it together — what to do this tax year

1. Track every business cost from day one in a single spreadsheet or accounting tool. Save receipts (a phone photo is fine).
2. Tag each cost as revenue or capital, and note the business-use percentage where it is mixed with personal use.
3. At year end, total the real expenses. If they are below £1,000, claim the trading allowance instead. If above, list the categories on your Self Assessment.
4. Use the side hustle tax calculator above to model both routes and confirm the actuals route is genuinely cheaper before filing.
5. Check borderline items (training, website builds, home-office layout, vehicle method) against the GOV.UK pages linked below before claiming.

This page is general guidance, not personal tax advice. Anything borderline — capital vs revenue calls, mixed-use apportionment, pre-trade expenses, partnership trades, VAT, or anything Scotland-specific — should be checked against the GOV.UK sources below or with a qualified adviser.