Yes, in most cases you do pay tax on a second income. If your extra earnings come from self-employment or a side hustle, the first £1,000 is covered by the trading allowance and is tax-free. Earn more than that, or take a second employed job, and the income is taxable on top of your main earnings.
The exact amount you owe depends on what the second income is, how much you earn in total, and which tax band the extra income falls into. Here are the UK rules for the 2026/27 tax year (6 April 2026 to 5 April 2027).
How much can I earn before paying tax on a second income?
It depends on the type of income.
- Self-employment or casual trading (eBay, Etsy, freelancing, dog walking, delivery driving): the first £1,000 of gross income is tax-free thanks to the trading allowance. Below this you usually don't need to tell HMRC.
- A second employed job: there is no separate tax-free amount. Your £12,570 personal allowance is normally used up by your main job, so the second job is typically taxed in full from the first pound.
- Property income (a lodger aside, renting out a room or space): a separate £1,000 property allowance applies, and the Rent a Room scheme can exempt up to £7,500.
If your only personal allowance has already been used by your main wage, every pound of a taxable second income is charged at your marginal rate. If your extra money comes from investments or property rather than active work, the treatment differs again, our guide to how passive income is taxed in the UK covers the rules in full.
What tax rate applies to my second income?
Your second income sits on top of your main income, so it's taxed at your highest band. The 2026/27 thresholds are:
| Band | Taxable income | Rate |
|---|---|---|
| Personal allowance | Up to £12,570 | 0% |
| Basic rate | £12,571-£50,270 | 20% |
| Higher rate | £50,271-£125,140 | 40% |
| Additional rate | Over £125,140 | 45% |
So if you already earn £45,000 in your main job, a £6,000 side income would push part of you into the higher-rate 40% band. You can model the combined effect with our income tax calculator.
Bear in mind the personal allowance tapers away by £1 for every £2 you earn over £100,000, so a second income can cost more than the headline rate once you cross that line.
Do I pay National Insurance on a second income?
Book a free Tax Health Check →
Possibly.
- Second employed job: Class 1 National Insurance is worked out separately on each job, so you may pay it twice if both pay above the primary threshold.
- Self-employed second income: you pay Class 4 NI on profits above £12,570, plus voluntary Class 2 if profits are below the small-profits threshold and you want to protect your state pension.
What about a second income from dividends?
If your side income is dividends from your own company or a share portfolio, the first £500 each year is covered by the dividend allowance. Above that, dividends are taxed at the new 2026/27 rates:
- 10.75% within the basic-rate band
- 35.75% within the higher-rate band
- 39.35% within the additional-rate band
The basic-rate (10.75%) and higher-rate (35.75%) dividend rates each rose by 2 points from April 2026, so dividends within those bands are now noticeably more expensive than in earlier years. The additional rate of 39.35% is unchanged.
Do I need to register for Self Assessment?
You must tell HMRC and file a Self Assessment tax return if:
- your gross self-employed or trading income exceeds £1,000 in the tax year, or
- you have untaxed income (rent, dividends above the allowance, foreign income), or
- you sell goods or services through online platforms and pass the reporting thresholds.
The quickest way to check is HMRC's own tool, Check if you need to tell HMRC about additional income. Note the £1,000 test is on gross income before expenses, not profit, a common and costly misunderstanding.
Deadlines you can't miss
- 5 October 2027, register for Self Assessment for the 2026/27 year.
- 31 January 2028, file your online return and pay any tax due.
Miss these and you face an automatic £100 penalty, rising the longer you leave it.
Trading allowance or actual expenses, which is better?
You can either claim the flat £1,000 trading allowance or deduct your real business expenses, but not both. Use the allowance if your costs are low (under £1,000); deduct actual expenses if your running costs are higher. You'll pay tax only on the resulting profit either way.
A worked example
Priya earns £38,000 in her main job and makes £4,500 (gross) freelancing on the side.
- She's over the £1,000 trading allowance, so she registers for Self Assessment.
- After £600 of expenses, her freelance profit is £3,900.
- Her main job uses her personal allowance and most of the basic-rate band. The £3,900 sits within the basic-rate band, taxed at 20% = £780, plus Class 4 NI.
Had the same profit tipped her over £50,270, the slice above would be taxed at 40%.
Frequently Asked Questions
How much can I earn from a second income before paying tax?
If the income is from self-employment or casual trading, the first £1,000 of gross income is covered by HMRC's trading allowance and is tax-free. A second employed job has no separate allowance, as your £12,570 Personal Allowance is normally used by your main job, so it is usually taxed from the first pound.
Do I have multiple trading allowances if I have several side hustles?
No. You get one £1,000 trading allowance in total, not one per side hustle. All your casual self-employed income, eBay sales, freelancing, delivery driving, shares the same £1,000 allowance, so add it together before deciding whether you must register.
What tax rate do I pay on a second income?
A second income sits on top of your main income and is taxed at your highest band. For 2026/27 that is 20% within the basic-rate band up to £50,270, 40% from £50,271 to £125,140, and 45% above that. Crossing a threshold means only the slice above it is taxed at the higher rate.
What if I earned untaxed second income in a previous year?
You should tell HMRC as soon as possible. If you missed declaring income from an earlier tax year, a voluntary disclosure usually attracts lower penalties than waiting for HMRC to find it, and interest is charged on any tax paid late. More answers are on our FAQ page.
Talk to a Zmartly accountant
If you're still weighing up where the extra money should come from, our roundup of passive income ideas for UK beginners is a useful starting point. A second income is great, an unexpected tax bill isn't. If you're unsure whether to declare, how to register, or which expenses you can claim, a quick chat can save you far more than it costs. Get in touch with Zmartly and we'll sort your second-income tax properly, on time, with no surprises in January.
