Self-Employments

Small Business Tax Tips UK — How to Legally Reduce Your Tax Bill

Practical strategies for UK small businesses and sole traders to legally reduce their tax bill, including allowable expenses, tax-efficient structures, and reliefs.

You have a legal obligation to pay the right amount of tax — but not a penny more. Here are practical ways to keep your tax bill to a minimum.

Tax-Saving Strategies by Business Type

Sole Traders

Strategy Detail Potential saving
Claim all allowable expenses Many sole traders miss legitimate deductions Varies — could be £1,000s
Working from home £6/week (simplified) or actual proportion of costs £312/year (simplified) or more
Mileage allowance 45p/mile (first 10,000) then 25p/mile Depends on mileage
Capital allowances Deduct cost of equipment from profits Full cost of qualifying items
Pension contributions Tax relief at your marginal rate Up to 45% tax relief
Use your partner If your spouse does genuine work, pay them (uses their tax-free allowance) Up to £12,570 tax-free
Trading allowance First £1,000 of trading income is tax-free £1,000
Losses Carry forward/back losses to offset against other income Reduces tax in profit years

Limited Company Directors

Strategy Detail Potential saving
Optimal salary/dividend split Pay salary just below NI threshold (~£12,570), rest as dividends £2,000–£10,000+/year
Employer pension contributions Company contributes to your pension — corporation tax deductible, no NI Up to £60,000/year
Company expenses Claim all legitimate business expenses through the company Varies
Capital allowances / AIA Deduct equipment costs — Annual Investment Allowance up to £1 million Full cost deduction
R&D tax credits If your company does innovative work 15–27% of qualifying spend
Salary sacrifice Sacrifice salary for pension, EV, cycle-to-work, ultra-low emission car NI savings for you and the company
Trivial benefits Gifts to employees/directors under £50 each (max £300/year for directors) Up to £300 tax-free
Shareholder spouse If your spouse is a genuine shareholder, dividends use their allowances Up to £2,000 dividend allowance each

Allowable Expenses Checklist

Sole Traders and Partnerships

Expense Allowable? Notes
Office supplies, stationery Yes
Business phone calls/contract Yes Business proportion only (if mixed use)
Internet Yes Business proportion
Postage Yes
Advertising and marketing Yes Including website costs, social media ads
Accountancy fees Yes
Legal fees (business-related) Yes
Professional subscriptions Yes Must be on HMRC’s approved list or directly relevant
Insurance (business) Yes Public liability, PI, etc.
Business travel Yes Mileage, public transport, hotels for business trips
Business meals (with clients/customers) Yes Must be genuinely for business entertainment
Working from home Yes £6/week simplified or actual costs
Training (related to current business) Yes Must improve existing skills, NOT learn a new trade
Stock and materials Yes
Uniforms/protective clothing Yes Only if specific to the job (not everyday clothes)
Equipment under £1,000 Yes Claim in full (or use capital allowances)
Bank charges and interest Yes Business accounts only
Bad debts Yes If you’ve written off an invoice you can’t collect
Software subscriptions Yes Business software

Limited Companies (Additional)

Expense Allowable? Notes
Director salary Yes Corporation tax deductible
Employer pension contributions Yes Corporation tax deductible, no NI
Employer NI Yes Deductible
Staff costs Yes
Business entertainment No Not allowable for CT (but no BIK if under £150/head for annual events)
Trivial benefits for directors Yes Under £50 each, max £300/year
Company car (electric/hybrid) Yes Very low BIK rates for EVs

Working From Home

Sole Traders

Method How it works Best for
Simplified expenses Flat rate: 25–67 hrs/month = £10/month, 51–100 hrs = £18/month, 101+ hrs = £26/month Simple, low costs
Actual costs Calculate proportion of home bills used for business Higher actual costs

Limited Company Directors

Method How it works Amount
Employer pays Company pays you £6/week (£26/month) for use of home as office — no evidence needed £312/year tax-free
Actual costs Company reimburses actual additional costs (must be evidenced) Varies
Rent a room Company pays a market-rate rent for use of a room — but CGT implications on property sale Consider carefully

Vehicle Expenses

Sole Traders — Mileage vs Actual Costs

Method Detail Best for
Mileage allowance 45p/mile (first 10,000) then 25p/mile Low-mileage or low-cost vehicles
Actual costs Claim proportion of fuel, insurance, servicing, depreciation High-mileage or expensive vehicles

Important: Once you choose a method, you must stick with it for that vehicle.

Limited Company — Company Car vs Personal Car

Option Tax treatment
Company car Benefit-in-kind tax based on CO₂ emissions. Electric = 2% BIK, Petrol = 20–37%
Personal car, claim mileage Company reimburses at HMRC advisory rates — tax-free
Personal car, claim 45p/mile Company pays 45p/mile as employee — same as sole trader rates

Pension Contributions

Scenario Tax benefit
Sole trader Contributions reduce taxable income — relief at 20/40/45%
Ltd company — employer contribution Corporation tax deductible (25% relief) AND no employee NI
Ltd company — salary sacrifice Saves both employer NI (13.8%) and employee NI
Annual allowance £60,000 (or 100% of earnings if lower)
Carry forward Use unused annual allowance from the previous 3 years

Capital Allowances

Type What it covers Allowance
Annual Investment Allowance (AIA) Plant and machinery 100% deduction up to £1 million/year
Full expensing (companies only) Plant and machinery 100% for main rate items, 50% for special rate
Writing down allowance Items not covered by AIA 18% (main pool) or 6% (special rate) per year
Small pools Pools under £1,000 Write off in full

Common Tax Mistakes

Mistake Cost
Not claiming all allowable expenses Overpaying tax
Not keeping receipts Can’t substantiate claims if HMRC enquires
Missing the Self Assessment deadline £100 fine + interest
Not registering for VAT when required Penalties and back-dated VAT owed
Taking too high a salary from a Ltd company Unnecessary NI charges
Not paying into a pension Missing significant tax relief
Not claiming mileage Free money left on the table
Mixing personal and business finances Record-keeping nightmare, risk of incorrect claims