UK Tax When You're Employed and Self-Employed

Many people begin freelancing while still employed — a side project that grows, consultancy work in evenings and weekends, or a portfolio career with several income streams running in parallel. If that is your situation, here is how the UK tax system handles it and what you need to do differently from someone who is purely employed or purely self-employed.

Do you need to register for Self Assessment?

Yes, in most cases. If your gross self-employment income is more than £1,000 in a tax year, you must register for Self Assessment with HMRC and file a return. You must register by 5 October following the end of the tax year in which you started freelancing.

The £1,000 figure is the trading allowance — a tax-free threshold on self-employment and trading income. If your freelance income is below £1,000, you do not need to register and owe no tax on it. The trade-off is that you also cannot claim any business expenses against that income. If your actual costs — software, equipment, professional subscriptions — exceed £1,000, registering and claiming expenses will almost always be more tax-efficient.

If you are not yet registered and your freelance income has exceeded £1,000, the step-by-step Self Assessment registration guide covers the full process, including your UTR number and Government Gateway account.

How income tax works when you're employed and self-employed

HMRC taxes all your income together. Your personal allowance (£12,570 in 2025–26) and income tax bands apply to your total income — employment salary plus freelance profit combined.

Your employer continues to deduct income tax and Class 1 National Insurance from your salary via PAYE. Your Self Assessment return then calculates any additional tax owed on your freelance profit, and you pay the difference to HMRC directly.

Here is a straightforward example:

	Amount
Employment salary	£30,000
Freelance profit (after expenses)	£10,000
Total income	£40,000
Personal allowance	−£12,570
Taxable income	£27,430

In this scenario, your employer taxes your salary through PAYE — including the portion of the personal allowance used against your employment income. The additional £10,000 of freelance profit is taxed at 20% basic rate via Self Assessment, resulting in an additional income tax bill of approximately £2,000.

National Insurance: two charges, not one

This is the part of dual-income taxation that most people underestimate, and it is worth understanding clearly.

As an employee, your employer deducts Class 1 NI from your salary at 8% on earnings between £12,570 and £50,270. This is handled automatically via PAYE — you do not deal with it directly.

As a sole trader, you also pay Class 4 NI on your freelance profits at 6% on profits between £12,570 and £50,270 (2025–26 rate), and 2% on anything above £50,270. Class 4 is calculated on your Self Assessment return and paid alongside your income tax.

Both sets of NI apply independently. You cannot offset Class 1 payments against Class 4 — they are separate charges on separate income streams.

The one exception: if your Class 1 and Class 4 contributions combined would exceed the annual NI maximum, there is a mechanism to limit your Class 4 liability. This is most relevant for people whose combined income significantly exceeds £50,270. If that describes your situation, it is worth raising with an accountant — overpayments are not automatically refunded and require a specific claim.

For the full picture on how Class 4 NI works — including the 2024 abolition of Class 2 and the State Pension implications — the National Insurance guide for UK sole traders covers it in detail.

What counts as freelance profit?

Your taxable freelance profit is your freelance income minus allowable business expenses. Commonly claimable expenses for freelancers include:

• Home office costs (a proportion of rent, heating, and electricity)
• Phone and broadband (the business-use proportion)
• Equipment and software directly used for freelance work
• Professional subscriptions and relevant training
• Travel to client sites (not commuting)

Every legitimate expense you claim reduces your taxable profit — which reduces both your income tax and your Class 4 NI bill. Accounting software handles categorisation as you go, so you are not piecing it together from memory at year end.

Record-keeping requirements

HMRC requires you to keep records of all freelance income and expenses for at least five years after the Self Assessment filing deadline. For most freelancers this means:

• All invoices issued
• Evidence of payments received (bank statements)
• Receipts and documentation for business expenses

A spreadsheet works if your freelance activity is modest. As income grows, accounting software like FreeAgent keeps everything in one place, automatically categorises transactions, and gives you a running estimate of your tax liability — so you know what you owe HMRC before January, not after.

How much to set aside for tax on your freelance income

Full-time sole traders typically save 25–30% of each payment for tax. With PAYE employment alongside, the picture is different:

• Your personal allowance is likely already used by your employment income
• Your freelance profit is therefore taxed from the first pound
• Set aside 20–25% of each freelance payment as a baseline
• If your combined income is approaching or above £50,270 — the higher-rate threshold — save 35–40% to cover higher-rate tax on your freelance profit

The sole trader tax saving guide explains the full system: how to structure a separate savings pot, how the payment on account system affects your January bill, and the exact dates to plan around. The system described there applies equally to those with mixed employment and self-employment income.

Practical steps when you're employed and self-employed

A few habits that make the combined income situation significantly cleaner:

• Open a separate account for freelance income. It keeps records clear and makes expense tracking simpler. A dedicated business current account is worth considering once your freelance income becomes regular.
• Set aside tax the day payment arrives. Not at month end — on the day the payment lands in your account. The money you do not see in your main account is the money you will not spend.
• Register for Self Assessment early in your first freelance year. Do not wait until the October deadline when you are unfamiliar with the process.
• Check your PAYE tax code. HMRC may adjust your code to collect additional tax on estimated freelance income in-year. This can create confusion if your freelance income is irregular — worth checking via your personal tax account on gov.uk.

When to get an accountant

For most people starting out with modest freelance income alongside employment, self-filing is manageable with good record-keeping and accounting software. A one-off professional consultation becomes worth the cost when:

• Your freelance income exceeds approximately £20,000–£30,000
• Your combined income is approaching a significant threshold (£50,270 or £100,000)
• You also have pension contributions, rental income, or investment income to factor in
• You want to confirm whether the NI deferral mechanism applies to your situation

If your annual freelance turnover is approaching £50,000, you should also check whether Making Tax Digital for Income Tax applies to you. MTD qualifying income is your gross self-employment and property income only — not your PAYE salary — but it is worth understanding the rules before April 2026.