The deductions you are not claiming (and what they cost you)
Quick answer
HMRC does not send a list of what you could have claimed. Pick your trade above, mark what you already claim, and see what the gaps cost you in real tax, then start keeping the evidence that turns them into savings.
Use the Self-Employed Expenses Checker
Your business
Pick your trade to prefill typical figures - then edit anything to match your year.
Every £1 you don't claim costs you
Your marginal rate: income tax + Class 4 NI = on every extra £1 of profit.
The most-missed expense categories
Tick "I claim this" for anything already in your return. Set an amount to £0 if it doesn't apply.
Business mileage
55p/mile for the first 10,000, then 25p - jobs, suppliers and clients (not commuting to one regular base).
Working from home (flat rate)
HMRC's simplified rate - no receipts needed, just a note of your hours.
Deductions you're missing
costing you about in extra tax every year at your marginal rate
- Tax you'd stop overpaying
Nothing obvious left on the table
You're claiming every category we check. Keep logging as you go so next January is painless.
Already filed? You can still fix it
Amend a Self Assessment return up to 12 months after its filing deadline, and overpayment relief can reach back four years for clear mistakes. Start keeping the evidence now - a photo of a receipt is enough.
Estimates, not advice - expenses must be wholly and exclusively for the business. Confirm each claim on GOV.UK before your return.
The rules in one paragraph
An expense must be wholly and exclusively for the business. Mixed-use costs (phone, home, car) are claimed in proportion. Everyday clothing never counts, even bought for work. Training counts when it updates existing skills, not when it teaches a brand-new trade. Pre-trade costs from up to 7 years before you started are treated as day-one expenses. And you need records - a photo of a receipt in a folder, or a mileage log, is enough.
Saved scenarios
| Scenario | Missed deductions | Tax saving | |
|---|---|---|---|
Source: GOV.UK official rates
Quick answer
Self-employed workers can deduct every cost that is wholly and exclusively for the business: typically worth £1,000 to £3,000 of deductions a year, which is £260 to £780 less tax for a basic-rate sole trader (26% saved per £1 including Class 4 NI). The checker above shows what your trade usually misses.
Why sole traders overpay
Every £1 of legitimate business expense you fail to claim adds £1 to your taxable profit, taxed at roughly 26% for a basic-rate sole trader (20% income tax plus 6% Class 4 National Insurance) and 42% at higher rate. Most under-claiming is not caution, it is simply not knowing an expense counts or not keeping the record at the time.
The most-missed claims
Mileage at 45p a mile (25p after 10,000) for trips to jobs, suppliers and clients. Working from home, either HMRC\'s flat rate of up to £26 a month or a share of actual bills. The business share of phone and internet. Washing protective or branded workwear. Tools and small equipment replaced through the year. Insurance, software, subscriptions, bank fees and advertising. Individually small, together they are commonly £1,000 to £3,000 of deductions a year.
The rules in one paragraph
An expense must be wholly and exclusively for the business. Mixed-use costs (phone, home, car) are claimed in proportion. Everyday clothing never counts, even bought for work. Training counts when it updates existing skills, not when it teaches a brand-new trade. And you need records: a photo of a receipt in a folder, or logged in an expense tracker, is enough.
Already filed? You can still fix it
A Self Assessment return can be amended up to 12 months after its filing deadline, and overpayment relief can reach back four years for clear mistakes. Going forward, log expenses as they happen and the January panic disappears.
HMRC's flat rates you can use without receipts
Working from home (simplified expenses)
| Business use at home | Flat rate | Per year |
|---|---|---|
| 25 to 50 hours/month | £10/month | £120/year |
| 51 to 100 hours/month | £18/month | £216/year |
| 101 or more hours/month | £26/month | £312/year |
Vehicle mileage
| Miles per year | Rate | Example claim |
|---|---|---|
| First 10,000 miles | 45p/mile | 8,000 miles = £3,600 |
| Above 10,000 miles | 25p/mile | 14,000 miles = £5,500 |
The full allowable list is on GOV.UK self-employed expenses and simplified expenses. Log as you go with the expense tracker and mileage tracker, then claim it all in the tax return wizard.
Reviewed by
Laura Michelle Davis - Chartered Tax Adviser (CTA)
ACCA · CTA (Chartered Tax Adviser) · ATT · BSc Economics, UC Berkeley
Laura Michelle Davis is a Chartered Tax Adviser (CTA) who also holds the ACCA and ATT qualifications and a BSc in Economics from UC Berkeley. She specialises in UK personal tax, covering income tax, National Insurance, self-employment and capital gains, and has built her career making complicated rules easy to follow. At TaxFly, Laura writes and edits the tax guides and explainers, checking that figures reflect current HMRC rates and that every explanation answers the question a real person is actually asking. Her goal is plain-English clarity you can trust and act on.
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Frequently asked questions
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