Self-Employment Tax: NICs, Allowable Expenses, Payments on Account, and the Ltd Company Decision

Self-employed people pay more tax than employees on the same income — and most of them don't fully understand why

An employee earning £50,000 pays income tax and employee National Insurance. A self-employed person earning £50,000 pays income tax, Class 4 NICs, and Class 2 NICs — and additionally bears the employer NI contribution that would otherwise be their employer's responsibility. The combined tax burden is structurally higher.

Understanding self-employment tax is the first step to operating tax-efficiently as a freelancer, contractor, or sole trader.

UK self-employment tax: the complete picture

Income tax

Self-employed income tax uses the same bands as employee income tax:

• Personal allowance: £12,570 (0%)
• Basic rate: £12,571–£50,270 (20%)
• Higher rate: £50,271–£125,140 (40%)
• Additional rate: above £125,140 (45%)

Profit (revenue minus allowable business expenses) is what's taxed — not gross revenue.

National Insurance for the self-employed (2024–25)

Class 2 NICs: a flat weekly charge. From April 2024, Class 2 NICs are being abolished for most self-employed people below a profits threshold. Previously: £3.45/week if profits above £12,570.

Class 4 NICs:

• 6% on profits between £12,570 and £50,270
• 2% on profits above £50,270

Compare to employed equivalent: An employee earning £50,000 pays 8% on £12,571–£50,270 in employee NI. A self-employed person earning £50,000 pays 6% Class 4 on the same band.

This appears cheaper — but the total picture includes what the employer pays: 13.8% employer NI on income above £9,100. A self-employed person bears this implicitly in their pricing.

Allowable business expenses: what reduces self-employed tax

The key advantage of self-employment over employment: legitimate business expenses reduce taxable profit.

Fully allowable:

• Office rent (for a separate business premises)
• Business phone and broadband (100% if business-only)
• Professional subscriptions and memberships
• Business insurance
• Equipment used entirely for business
• Software subscriptions for work
• Accountancy fees
• Business travel (not commuting to a fixed place of work)
• Advertising and marketing
• Staff costs (if any employees)

Partially allowable (business use proportion):

• Home office costs (using HMRC flat rate or proportion of household bills)
• Vehicle costs (proportion based on business mileage)
• Phone/broadband with mixed use (business proportion only)

HMRC flat rates for simplicity:

• Home office: £6/week (no receipts needed)
• Or actual costs: calculate business floor space % × household bills
• Vehicle: 45p/mile for first 10,000 business miles, 25p/mile thereafter

Quarterly tax payments (payment on account)

Employees pay tax via PAYE — deducted from salary before receipt. Self-employed pay through Self Assessment, with payments on account:

First payment on account: January 31 (50% of previous year's tax bill) Second payment on account: July 31 (50% of previous year's tax bill) Balancing payment: January 31 the following year (remaining tax due or refund)

The cash flow trap: in the first year of self-employment, no payments on account were made during the year. The first tax bill (January 31 following the tax year) includes:

• Full year's tax (balancing payment for year 1)
• First payment on account for year 2 (50% of year 1 bill)
• Second payment on account due July 31 (another 50%)

A first-year self-employed person can face a tax bill of 200% of one year's liability on January 31.

Solution: set aside approximately 25–30% of each invoice received in a dedicated tax account as you go.

Sole trader vs limited company: the tax comparison

Beyond sole trader status, freelancers can incorporate as a limited company. This creates different (often lower) tax options:

Limited company tax advantages:

• Corporation tax: 19–25% (lower than 40% income tax for higher earners)
• Salary/dividend combination: pay yourself a small salary (just above primary NI threshold) + dividends from company profits
• Dividends have lower rates than income: 8.75% (basic rate), 33.75% (higher rate)
• Employer pension contributions from the company are tax-deductible

Example at £60,000 profit:

Accounting cost: limited companies require more administration — annual accounts, corporation tax return, director filings. Typically £1,000–2,000/year in accountancy fees vs £300–600 for sole trader accounts.

The tax saving needs to exceed the additional administration cost to justify incorporation.

How to use the Tax Calculator on sadiqbd.com

1. Enter self-employed income/profit — after deducting allowable expenses
2. Calculate income tax + Class 4 NICs
3. Estimate quarterly payments — divide annual liability to plan cash flow
4. Compare sole trader vs limited company — run both scenarios

Frequently Asked Questions

Do I need to register for VAT as a self-employed person? VAT registration is compulsory when taxable turnover exceeds £90,000 in any 12-month period (2024–25). Below this threshold, registration is optional. Registered businesses charge 20% VAT on most services and can reclaim input VAT on business expenses. For B2B clients who are also VAT-registered, being VAT-registered may be neutral. For B2C (individual) clients, adding 20% to prices reduces competitiveness.

Is pension contribution the best tax planning tool for self-employed? Personal pension contributions (SIPP or personal pension) attract full tax relief at the individual's marginal rate. A self-employed person in the 40% bracket contributing £10,000 to a SIPP effectively costs £6,000 after 40% tax relief (£2,500 basic rate claimed automatically + £2,500 further relief via Self Assessment). This also reduces the adjusted net income below the £100,000 threshold, potentially restoring the personal allowance.

Is the Tax Calculator free? Yes — completely free, no sign-up required.

Try the Tax Calculator free at sadiqbd.com — calculate self-employment tax, Class 4 NICs, and compare different income structures.