I Have a Full-Time Job and a Side Hustle. How Does Tax Work? UK Guide for 2026/27
If you have a full-time job and make some extra money on the side, you might be wondering what happens with tax.
The short answer is: your salary and your side hustle income are both taken into account when working out how much Income Tax you owe.
Your employer will normally continue deducting tax from your salary through PAYE as usual. If your side hustle needs to be reported to HMRC, you will generally declare your self-employed income and expenses separately through Self Assessment.
And no, having a full-time job does not automatically mean you need to pay 40% tax on everything you make from your side hustle.
Let's break it down:
Do I have to pay tax on a side hustle if I already have a job?
Potentially, yes.
Being employed does not give you a separate tax-free allowance for your side hustle.
For the 2026/27 tax year, most people have a Personal Allowance of £12,570. Your income from different taxable sources is then considered together when calculating your overall Income Tax position.
For someone in England, Wales or Northern Ireland, the main 2026/27 Income Tax bands are:
20% basic rate up to the basic-rate limit, 40% higher rate above that, and 45% additional rate at the highest level.
For most people with a full-time job, some or all of their Personal Allowance will already be used against their salary. That means additional taxable profit from a side hustle could effectively sit on top of their employment income.
Scottish Income Tax bands and rates are different.
What is the £1,000 side hustle allowance?
This is where one of the biggest misunderstandings comes in.
There is a £1,000 trading allowance for certain trading and casual income.
If your gross trading income is £1,000 or less during the tax year, you will often not need to tell HMRC about it.
The important word there is gross.
It is your income before expenses, not your profit.
So if you receive £1,200 from customers but spend £500 on costs, your profit might only be £700, but your gross trading income is still above £1,000.
Once your gross trading income exceeds £1,000, you will normally need to consider registering for Self Assessment.
You can potentially use the £1,000 trading allowance when calculating your taxable profit instead of claiming your actual business expenses. You cannot normally claim both the trading allowance and your actual expenses against the same income, so it is worth checking which gives you the better result.
Is side hustle tax based on turnover or profit?
Usually, you pay Income Tax on your taxable profit, not simply on all the money that comes into the business.
Imagine you make £6,000 from your side hustle during the year.
You have £1,500 of allowable business expenses.
Your starting profit would therefore be £4,500.
It is that profit figure, subject to any relevant tax adjustments, that feeds into your tax calculation.
This is why keeping track of legitimate business expenses matters. Things such as software, certain phone costs, business travel, advertising, professional fees and other costs incurred for your business may be allowable depending on the circumstances.
HMRC publishes specific rules on what self-employed people can and cannot claim.
How much tax will I pay on my side hustle?
It depends mainly on how much you earn from your job and how much taxable profit you make from the side hustle.
Example 1: £35,000 salary and £5,000 side hustle profit
Imagine you earn £35,000 from your job and make £5,000 of taxable profit from your side hustle.
Your total income is still within the basic-rate band, assuming no other income or complications.
Broadly, your £5,000 side hustle profit would therefore be subject to 20% Income Tax.
That would mean approximately £1,000 of additional Income Tax on the £5,000 profit.
Because the side hustle profit itself is below the current Class 4 National Insurance threshold, there would not normally be Class 4 National Insurance on that £5,000.
Example 2: £45,000 salary and £10,000 side hustle profit
Now imagine your salary is £45,000 and your side hustle generates £10,000 of taxable profit.
Part of that extra profit takes your total income above the higher-rate threshold.
That means part of your side hustle profit could be taxed at 20% and part at 40%.
This is why the answer to "what percentage should I put aside for tax?" is not always simply 20%.
Your employment income matters too.
These examples are deliberately simplified and assume the standard Personal Allowance, no other taxable income and the Income Tax rates applying in England, Wales and Northern Ireland.
Do I pay National Insurance on my side hustle as well?
Possibly.
If you are employed, you will normally already pay Class 1 National Insurance through your wages.
Self-employed people can also become liable for Class 4 National Insurance based on their self-employed profits.
For 2026/27, Class 4 National Insurance generally applies when self-employed profits exceed £12,570. The standard rates are currently 6% on profits between £12,570 and £50,270 and 2% above that.
People who are both employed and self-employed can have both Class 1 and Class 4 National Insurance to consider. HMRC applies rules around the combined position, so larger or more complicated cases are worth checking properly rather than simply adding the two together.
When do I need to register my side hustle with HMRC?
If your gross trading income is more than £1,000 in a tax year, you will usually need to register for Self Assessment if you are not already registered.
And there is an important deadline approaching at the time of writing.
If you need to complete a tax return for the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026, and you have not previously registered, you should tell HMRC by 5 October 2026.
So if your side hustle went beyond the £1,000 threshold during 2025/26 and you have not yet done anything about it, now is a good time to check.
Will my employer know I have a side hustle?
Your employer does not automatically deal with the tax affairs of your separate self-employed business.
Your normal salary will continue to go through PAYE, while your self-employed income is dealt with separately.
You should, however, check your employment contract for any clauses relating to outside work, competing businesses or conflicts of interest.
Can HMRC collect my side hustle tax through my PAYE code?
In some situations HMRC may be able to collect smaller Self Assessment liabilities through your PAYE tax code, subject to its rules and limits.
But you should not assume this will happen.
If you are completing Self Assessment, plan on the basis that you may need to pay the amount due yourself unless HMRC confirms otherwise.
Why can the first Self Assessment tax bill feel so big?
This catches a lot of new sole traders out.
In some circumstances, HMRC asks for payments on account towards the following year's tax bill.
These normally apply unless your previous Self Assessment tax liability was less than £1,000 or more than 80% of the tax you owed was already collected outside Self Assessment.
Each payment on account is normally half of the previous year's relevant tax bill, with payments due on 31 January and 31 July.
So somebody filing their first return could potentially have their actual tax bill to pay on 31 January plus the first payment towards the following year's bill.
That does not mean HMRC is taxing the same profit twice. The extra amount is an advance payment towards the next tax year.
How much should I put aside for side hustle tax?
There is no single percentage that works for everybody.
The best approach is to look at where your employment income already puts you within the tax bands, estimate your expected side hustle profit and then save towards the likely tax and National Insurance bill.
In particular, do not automatically assume saving 20% is enough just because you think of yourself as a basic-rate taxpayer.
A profitable side hustle can push some of your income into a higher tax band.
Having a separate savings account for tax can make this much easier. Move money across regularly rather than waiting until January and discovering that the money has quietly become part of your everyday spending.
Future You will be grateful.
Does Making Tax Digital affect people with a job and a side hustle?
It can.
Making Tax Digital for Income Tax started applying to some sole traders and landlords from 6 April 2026.
The important point is that the thresholds are based on qualifying gross income from self-employment and property, not your PAYE salary.
People with qualifying income above £50,000 based on their 2024/25 tax return came into MTD from April 2026.
The threshold falls to more than £30,000 from April 2027, based on qualifying income reported for 2025/26, and more than £20,000 from April 2028, based on 2026/27 qualifying income.
So someone earning £60,000 from their job and £5,000 from their side hustle would not enter MTD simply because their combined income was £65,000. It is the relevant self-employment and property income that matters for the MTD threshold.
What should I do if my side hustle is growing?
Once a side hustle starts making regular money, the admin becomes much easier if you get things organised early rather than trying to rebuild everything at tax-return time.
A sensible starting point is:
Keep your business income and expenses organised.
Keep copies of receipts and invoices.
Check whether your gross income has passed the £1,000 trading allowance threshold.
Register for Self Assessment when required.
Understand which expenses you can legitimately claim.
Estimate your tax bill during the year and put money aside for it.
Check whether Making Tax Digital is likely to affect you now or in the next couple of years.
You don't need a complicated finance department for a side hustle.
You do need a system that lets you understand what you're earning, what you're spending and what HMRC is going to expect from you.
Frequently asked questions about side hustle tax
Do I pay tax on my side hustle if I earn less than £1,000?
If your total gross trading income is £1,000 or less during the tax year, the trading allowance will often mean you do not need to report it to HMRC. There are exceptions, so check the rules if you need to complete a tax return for another reason or want to claim certain reliefs.
Does my £1,000 trading allowance reset every year?
Yes. The trading allowance applies for each tax year.
Is the £1,000 allowance based on profit?
No. The £1,000 threshold looks at gross trading income before expenses.
Do I get another £12,570 Personal Allowance for my side hustle?
No. You do not receive a separate Personal Allowance for each job or business. Your taxable income is considered together.
Can I be employed and self-employed at the same time?
Yes. It is completely possible to have PAYE employment while also operating as a sole trader.
Do I need an accountant for a small side hustle?
Not necessarily. Plenty of straightforward sole traders manage their own records and Self Assessment.
What matters is understanding the rules that apply to you and having decent records. As the business becomes larger or more complicated, getting professional advice may save you considerably more than it costs.
The simple version
If you have a full-time job and a side hustle, don't panic about tax.
Your job can carry on through PAYE as normal.
Keep track of how much your side hustle actually brings in. Once gross trading income goes above £1,000, check whether you need to register for Self Assessment.
Keep records of your genuine business expenses, understand that the tax is generally calculated on your profit, and remember that your side hustle profit sits alongside your other taxable income when your overall tax bill is calculated.
Most importantly, put some of the money aside as you earn it.
A tax bill is considerably less painful when the money is already waiting for it.
Want a hand getting your tax organised?
Hustle Mate is built for side hustlers, sole traders and small business owners who want to understand this stuff without having to become accountants themselves.
This month's Self-Employment Tax Playbook brings the key information together in one practical resource, including the numbers, deadlines and things you actually need to keep on top of.
It's available inside the Hustle Mate member library alongside our templates, guides and practical tools for running your business.
Already a member? Head to the library and download the Self-Employment Tax Playbook.
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This article is general information based on UK tax rules at the time of writing and isn't personalised tax advice. Your circumstances can affect the tax you pay.
