How Much Tax Do I Owe on My Side Hustle? A Complete Guide for UK Workers

If you earn money outside your main job — freelancing, selling online, delivering, tutoring, or anything else — HMRC expects a cut. The problem is that your employer's PAYE only covers your salary. Your side hustle sits completely outside that system, and it's your responsibility to declare it and pay the tax yourself.

This guide explains exactly how side hustle tax works in the UK, what you'll actually owe, and how to avoid getting caught out by an unexpected bill.

Do I actually need to pay tax on my side hustle?

Yes — all income you earn in the UK is taxable, including side hustle income. However, there is one important exception: the £1,000 trading allowance.

If your total gross self-employment income is under £1,000 in a tax year, you don't need to declare it or pay any tax on it. You also don't need to register with HMRC.

Once your income goes above £1,000, you must register for Self Assessment and declare everything you earn — even if you end up owing little or no tax after expenses.

How is side hustle income taxed?

This is where a lot of people get a surprise. Your side hustle profit isn't taxed in isolation — it's added on top of your salary and taxed using the same income tax bands.

That matters because your salary already uses up the lower, cheaper tax bands. Your side hustle income starts from wherever your salary left off.

Do I pay National Insurance on my side hustle?

Yes. As well as income tax, you pay Class 4 National Insurance on self-employment profits above £12,570.

For 2026/27 the rates are:

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

Your employer already deducts Class 1 employee NI from your salary, but that doesn't cover your self-employment income — Class 4 is an additional charge on top.

Class 2 NI was effectively abolished from April 2024, so most side hustlers only need to worry about Class 4.

What is Self Assessment?

Self Assessment is HMRC's system for collecting tax on income that isn't handled through PAYE. Every year you fill in a tax return declaring all your income sources, HMRC works out what you owe, and you pay it.

Key dates to know:

• 5 October — deadline to register for Self Assessment (in the year after you first earned over £1,000)
• 31 January — deadline to file your online return and pay any tax owed
• 31 July — second payment on account (if HMRC requires advance payments)

What are payments on account?

This is the part that catches most people out in year two. Once your Self Assessment bill exceeds £1,000, HMRC requires you to make advance payments towards the following year's bill.

These are called payments on account:

• 50% of your current bill is due on 31 January (alongside your actual bill)
• Another 50% is due the following 31 July

That means in year two you could effectively pay 150% of your bill in one go — your actual tax plus the first advance payment. Setting money aside monthly from day one is the only way to avoid this being a shock.

What expenses can I claim?

You can reduce your taxable profit by deducting costs that are wholly and exclusively for your business. Common allowable expenses include:

• Equipment and tools used for work (laptops, cameras, machinery)
• Business mileage — 45p per mile up to 10,000 miles, 25p after
• Software and subscriptions used for the business
• A proportion of your home broadband and phone bill
• Home office costs — HMRC flat rate of £6/week with no receipts required
• Marketing — website hosting, ads, business cards
• Accountant or bookkeeper fees
• Professional insurance

You cannot claim personal food, everyday clothing, commuting costs, or anything that isn't exclusively for business use. Keep receipts for everything — HMRC can ask for evidence up to six years later.

What is the £1,000 trading allowance?

If your actual business expenses are low, you may be better off using the trading allowance — a flat £1,000 deduction instead of calculating your real costs.

It's simpler, requires no receipts, and is worth using if your actual expenses come to less than £1,000. You can't combine it with actual expenses — it's one or the other.

If your gross income is under £1,000, the allowance covers everything and you don't need to declare it at all.

How much should I set aside each month?

As a rough rule of thumb, setting aside 25–30% of your side hustle profit each month will usually cover your income tax and Class 4 NI. But the exact amount depends on your salary, how much you earn from the side hustle, and what tax band you fall into.

The safest approach is to calculate your exact figure rather than guess — that way you're not over or under saving.