Earning £5,000 From a Side Hustle: The Tax You Actually Owe in 2026/27

Past the Trading Allowance: Why £5,000 Must Be Declared

The £1,000 trading allowance is a genuinely useful perk. It lets anyone earn up to £1,000 of gross self-employed or casual income in a tax year without paying tax on it - and without even needing to tell HMRC. Sell a few things online, do a bit of freelance work, rent out your drill on a sharing app: under £1,000 gross, it is yours to keep.

But £5,000 of profit is five times that limit. Once your gross trading income exceeds £1,000 in a tax year you must:

1. Register for Self Assessment (by 5 October following the end of the tax year).
2. File a tax return reporting the income.
3. Pay any income tax and National Insurance due.

For the 2026/27 tax year, your online return and payment are both due by 31 January 2028.

Income Tax: It Stacks On Top of Your Salary

The key thing to understand is that side-hustle profit does not get its own personal allowance. It sits on top of your employment income, so it is taxed at whatever your top marginal rate already is.

Assume your job already uses up the £12,570 personal allowance. The £5,000 of side profit is then taxed entirely at your marginal rate.

Note the example assumes you claim the £1,000 trading allowance rather than deducting actual expenses, which reduces your taxable profit from £5,000 to £4,000.

Watch the band boundary

If your salary is, say, £48,000, then £2,270 of the side profit fits in the basic-rate band and the remaining £2,730 of taxable profit is taxed at 40%. Side income can straddle the £50,270 threshold, so part of it can be taxed at 20% and part at 40% in the same year.

Class 4 National Insurance: The Often-Forgotten Bit

Self-employed profits also attract Class 4 National Insurance once total profits exceed £12,570. In 2026/27 Class 4 is charged at:

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

Because your side hustle adds to your overall self-employed profit position, the £4,000 of taxable side profit (after the trading allowance) generally attracts Class 4 at 6% if your total income keeps you in the main band:

• £4,000 x 6% = £240

If the side income tips you over £50,270, the slice above that is charged at just 2%. Class 2 NICs are no longer separately payable for most people, having been effectively removed, though voluntary Class 2 can still be paid to protect benefit entitlements.

Putting It Together: Your Total Bill

Here is the full position on £5,000 of side-hustle profit, after claiming the £1,000 trading allowance, for two common scenarios.

So you keep roughly £3,960 of your £5,000 as a basic-rate taxpayer, or roughly £3,200 as a higher-rate taxpayer. The exact NI depends on where the profit falls relative to £50,270.

Allowance or Expenses: Pick the Bigger Deduction

You face a choice each year and cannot use both:

• Claim the £1,000 trading allowance - a flat deduction, no record-keeping of costs needed.
• Deduct actual allowable expenses - things like materials, software, mileage, a proportion of home costs, marketing and platform fees.

The rule of thumb is simple: if your genuine business expenses are below £1,000, claim the allowance. If they are above £1,000, deduct the real figures and keep your receipts.

On a £5,000 side hustle with only £400 of costs, the trading allowance wins - it gives £1,000 of relief instead of £400, saving you tax on the extra £600.

Don't Forget Payments on Account

The first year of a side hustle often produces a nasty surprise. If your total Self Assessment bill exceeds £1,000, HMRC will usually ask for payments on account - two advance instalments towards next year's tax, each equal to half of this year's bill.

So a £1,040 bill for 2026/27, due 31 January 2028, could be accompanied by a first payment on account of £520 due the same day, and a second £520 due 31 July 2028. Your January demand effectively becomes £1,560. Budget for this - it catches out almost every first-time filer.

A Simple Side-Hustle Tax Routine

1. Open a separate bank account or pot for the business so income is easy to track.
2. Set aside roughly 30% of every payment for tax and NI (more if you are a higher-rate taxpayer).
3. Keep a running record of income and expenses from day one.
4. Register for Self Assessment as soon as you pass £1,000 gross.
5. File and pay by 31 January, and plan for payments on account in year one.

Putting aside 30% as you go means the January bill is already covered, and any surplus is a small bonus.

Key Takeaways

• The £1,000 trading allowance is tax-free; above it you must declare everything.
• £5,000 of profit, less the £1,000 allowance, leaves £4,000 taxable, stacked on top of your salary.
• Income tax is £800 at basic rate or £1,600 at higher rate; Class 4 NI adds roughly £240.
• Total bills typically run from about £1,040 to £1,840 depending on your band.
• Watch out for payments on account, which can roughly inflate your first January demand by half again.

Estimate your own side-hustle bill with the Self-Employed Tax calculator.