Employed + Self-Employed: UK Tax Guide 2026/27

Yes, You Can Do Both

Millions of people in the UK hold a PAYE job while running a business on the side - whether that is freelancing, selling on Etsy, tutoring, or contracting. HMRC has no issue with this arrangement. You simply have two sources of income, each with its own tax treatment.

Your employer continues to deduct income tax and Class 1 National Insurance from your salary through PAYE. Your self-employed profits are declared separately through Self Assessment. The key thing to understand is how these two income streams interact when it comes to tax bands and National Insurance.

How Income Tax Works on Combined Income

HMRC does not treat your employment income and self-employed profits as separate pots for income tax purposes. They are added together to determine your total taxable income and which tax band applies.

For the 2026/27 tax year, the income tax bands are:

Personal Allowance: the first £12,570 is tax-free. Basic rate: 20% on income from £12,571 to £50,270. Higher rate: 40% on income from £50,271 to £125,140. Additional rate: 45% on income above £125,140.

Your PAYE salary typically uses your Personal Allowance first. So if you earn £35,000 in your day job, your allowance is already used up - meaning every pound of self-employed profit is taxed at 20% from the first pound. If your combined income pushes you above £50,270, the portion above that threshold is taxed at 40%.

National Insurance: Two Systems, Not Double Tax

This is where most people get confused. National Insurance for employees and self-employed people operates under different classes, and each is calculated independently on its respective income.

On your employment income: you pay Class 1 NICs at 8% on earnings between £12,570 and £50,270 per year, and 2% above that. Your employer deducts this through PAYE - you do not need to do anything extra.

On your self-employed profits: you pay Class 4 NICs at 6% on profits between £12,570 and £50,270, and 2% above that. This is calculated and paid through your Self Assessment tax return.

Class 2 NICs are no longer compulsory for most self-employed people from 2024/25 onwards, though you can still pay them voluntarily (£3.65 per week in 2026/27) to protect your State Pension entitlement if your profits are below the Small Profits Threshold of £7,105.

Because the Class 4 lower profits limit starts at £12,570 regardless of what you earn in employment, you effectively get a second NI-free threshold on your self-employed income. This is a genuine advantage - your employment does not reduce your Class 4 threshold.

The £1,000 Trading Allowance

If your total gross self-employed income is £1,000 or less in the tax year, you can claim the trading allowanceA £1,000 tax-free allowance for casual or self-employed income. You can earn up to £1,000 before declaring, or deduct the flat £1,000 instead of your actual expenses - not both. and you do not need to register for Self Assessment or report the income to HMRC at all. This applies even if you also have a PAYE job.

If your gross income exceeds £1,000, you have a choice: deduct the £1,000 trading allowance from your income instead of claiming actual expenses, or claim your actual business expenses in the normal way. You cannot do both. For most small side hustles with minimal expenses, the trading allowance is simpler. For a business with significant costs (materials, software, travel), claiming actual expenses will usually save you more.

A Worked Example

Sarah earns £40,000 from her marketing job (PAYE) and makes £12,000 net profit (after expenses) from freelance design work on the side. Here is how her 2026/27 tax breaks down:

Income tax: Her combined taxable income is £52,000. After the £12,570 Personal Allowance, she pays 20% on the next £37,700 (= £7,540) and 40% on the remaining £1,730 above £50,270 (= £692). Total income tax: £8,232.

Class 1 NICs (employment): 8% on £27,430 (the portion of her £40,000 salary between £12,570 and £40,000) = £2,194. Already deducted by her employer.

Class 4 NICs (self-employment): 6% on the full £12,000 profit (all within the £12,570 to £50,270 band) = £720. Paid through Self Assessment.

Most of Sarah's income tax is handled through PAYE, but because her employer does not know about the freelance income, she will owe the tax on the self-employed portion (plus the higher-rate slice - the part of her income above the £50,270 higher-rate threshold) through her Self Assessment return. HMRC may adjust her tax code to collect some of this through PAYE if the amount is small enough.

When You Need to Register for Self Assessment

You must register for Self Assessment with HMRC if your gross self-employed income exceeds £1,000 in the tax year. You need to register by 5 October following the end of the tax year in which you started your side business, and file your return by 31 January (online) or 31 October (paper).

If you are already registered for Self Assessment (for example, because you have other untaxed income), you simply add the self-employment pages (SA103) to your existing return.

Making Tax Digital from April 2026

Making Tax Digital for Income Tax (MTD ITSA) launched in April 2026 for self-employed individuals and landlords with combined gross income above £50,000. From April 2027, the threshold drops to £30,000, and from April 2028 to £20,000.

If you are affected, you must keep digital records using MTD-compatible software and submit quarterly updates to HMRC instead of a single annual Self Assessment return. Your PAYE employment income is not included in the MTD requirement - it is your self-employed and property income that determines whether you are above the threshold.

Separately, digital platforms (such as Etsy, Fiverr and Upwork) have had to report seller income directly to HMRC under rules in force since January 2024 (first reports were due in January 2025), so unreported side income is increasingly visible to HMRC.

Practical Tips

Keep your finances separate. Open a dedicated bank account for your side business. This makes it far easier to track income and expenses and provides a clean audit trail if HMRC ever enquires.

Set aside money for tax. PAYE handles your employment tax automatically, but the tax on your self-employed income arrives as a lump sum (or two payments on account). A good rule of thumb is to set aside 30% of your self-employed profit if you are a basic-rate taxpayer, or 45% if your combined income puts you into the higher-rate band.

Check your employment contract. While there is no legal requirement to tell your employer about a side business, many employment contracts include restrictive covenants covering outside work, especially in competing industries. Breaching these could have serious consequences.

Claim your expenses. If your side business has genuine costs - equipment, software, travel, home office - you can deduct these from your profits before tax. See our guide to allowable expenses for what qualifies under the "wholly and exclusively" rule.