Side Hustle Tax UK: The Complete Guide for 2026/27

Millions of people in the UK earn income alongside their main job -- from freelancing, selling on eBay, renting out a room, driving for delivery platforms, tutoring, or hundreds of other activities. The tax rules for this extra income have become more important to understand in 2026/27, with HMRC actively using platform data to identify undeclared income and compliance activity increasing. Here is everything you need to know.

The GBP 1,000 Trading Allowance

The trading allowance is the starting point for every side hustler. If your total gross income from self-employment or miscellaneous trading is GBP 1,000 or less in a tax year, you pay no tax and do not need to tell HMRC.

The allowance applies to gross income -- before any expenses. You cannot use both the trading allowance and claim actual expenses.

If your gross income exceeds GBP 1,000, you have two options:

1. Deduct the GBP 1,000 trading allowance from gross income and pay tax on the remainder
2. Deduct actual allowable expenses from gross income

Choose whichever gives the lower taxable profit.

Example: Freelance photographer earns GBP 9,000 gross with GBP 2,200 in real expenses.

• Using trading allowance: GBP 9,000 - GBP 1,000 = GBP 8,000 taxable profit
• Using actual expenses: GBP 9,000 - GBP 2,200 = GBP 6,800 taxable profit

Actual expenses win here. But if expenses were only GBP 600, the trading allowance (GBP 1,000) would produce a lower taxable profit.

When Do You Need to Register for Self Assessment?

Register with HMRC if:

• Your gross self-employment income exceeds GBP 1,000 in a tax year, OR
• You have other untaxed income (rental, dividends, foreign income) that pushes you over thresholds, OR
• Your total income from all sources exceeds GBP 100,000 (additional obligations apply)

Registration deadline: 5 October following the end of the tax year.

For 2026/27 (year ending 5 April 2027): register by 5 October 2027.

Register online at gov.uk/register-for-self-assessment. You will receive a Unique Taxpayer Reference (UTR) by post in around 10 to 21 days.

Self Assessment filing deadlines for 2026/27:

Income Tax on Side Hustle Profits

Your self-employment profits are added to your employment income and taxed together. The combined figure determines which rate band applies.

2026/27 income tax bands:

Example: Employed at GBP 38,000 salary plus GBP 8,000 side hustle profit after expenses.

• Total income: GBP 46,000
• Less personal allowance: GBP 12,570
• Taxable income: GBP 33,430
• All in basic rate band: 20% x GBP 33,430 = GBP 6,686 total income tax
• Additional income tax from side hustle vs no side income: approximately GBP 1,600 (20% on GBP 8,000)

National Insurance on Self-Employment Income in 2026/27

Class 2 NI was abolished from 6 April 2024. No flat weekly contribution is due from self-employed individuals anymore.

The only self-employment NI in 2026/27 is Class 4:

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

If your self-employment profits are below GBP 12,570, you pay no Class 4 NI in 2026/27.

Example: Side hustle profits of GBP 18,000 on top of a GBP 30,000 employment salary.

Self-employment profits fall within the Class 4 range (GBP 12,570 to GBP 50,270), so: Class 4 NI = 6% x (GBP 18,000 - GBP 12,570) = 6% x GBP 5,430 = GBP 325.80

Note: employee NI on employment income is calculated separately through PAYE and is not affected by self-employment profits for Class 4 purposes.

Voluntary Class 3 NI and State Pension Credits

The abolition of Class 2 NI means that self-employed people with profits below GBP 12,570 no longer automatically build qualifying years toward their State Pension (currently GBP 241.30 per week in 2026/27 for those with a full record of 35 qualifying years).

If your self-employment profits are below GBP 12,570, consider paying voluntary Class 3 NI (GBP 824.20 for a full year in 2026/27) to protect your State Pension entitlement. One qualifying year of State Pension is worth approximately GBP 290 per year in extra pension for life. Most people with gaps recover the Class 3 cost within three years of retirement.

Allowable Expenses: What You Can Deduct

To reduce taxable profit, claim all expenses incurred wholly and exclusively for the trade.

Common allowable deductions:

• Materials and stock: Anything purchased to create or provide what you sell
• Home office (flat rate): GBP 10/month (25-50 hours worked at home), GBP 18/month (51-100 hours), GBP 26/month (over 100 hours)
• Home office (actual): Proportion of rent or mortgage interest, council tax, utilities based on rooms and hours used for business
• Equipment: Computers, cameras, tools -- claim 100% in year of purchase under the Annual Investment Allowance
• Business mileage (own car): 45p per mile for the first 10,000 business miles, 25p per mile above 10,000
• Phone and internet: A reasonable business-use proportion of your bills
• Professional fees: Accountancy, legal advice relating to the business
• Marketing: Website, social media ads, business cards, printing
• Training: Courses that update existing skills in your current trade (not unrelated new skills)

You cannot deduct personal costs, travel between home and a regular workplace, or clothing (unless specialist protective gear).

Record Keeping

HMRC expects you to keep records for at least 5 years after the 31 January submission deadline for each tax year. Keep:

• Invoices and receipts (digital copies are acceptable)
• Bank statements showing business income and expenses
• A mileage log if claiming business mileage
• Records of any business use of your home

Good record keeping also makes completing your Self Assessment return much faster.

Payments on Account: Cash Flow Warning

Once your annual Self Assessment tax bill exceeds GBP 1,000 and more than 20% of your income is untaxed at source, HMRC requires payments on account -- advance instalments of next year's expected tax liability.

This creates a cash flow challenge in the first year: in January you pay both the current year's tax bill and 50% of the following year's estimated bill simultaneously.

Plan ahead: Set aside 25-30% of gross side hustle income throughout the year as a tax reserve. Do not spend it. Transfer it to a separate account each month and earn interest on it until the deadline arrives.

HMRC Platform Data-Sharing

From January 2024, digital platforms must report to HMRC annually where sellers make 30 or more transactions or earn over EUR 2,000 (approximately GBP 1,700) in a year. Platforms covered include eBay, Vinted, Etsy, Amazon Marketplace, Airbnb, Uber, Deliveroo, and many others.

HMRC cross-references this data against declared income and tax returns. If you have been selling regularly on these platforms and not declaring income above GBP 1,000, expect HMRC contact.

Important distinction: Selling your own second-hand possessions at or below what you paid is not trading. Regular buying of goods with the intention of reselling for profit is trading, regardless of the platform. The badges of trade (frequency of transactions, profit motive, financing, modifications) determine whether activity is taxable trading.

Calculate Your Side Hustle After-Tax Income

Before you can set realistic earnings targets or pricing for your services, you need to know what you actually keep after income tax and Class 4 NI. Use the CalcHub self-employed tax calculator to enter your employment income and side hustle profit together, see your total tax and NI bill, and calculate your effective take-home rate. It also models the payments on account you will face so you can plan your cash reserves from day one.