Taking on a second job can be a great way to boost your income — whether you’re freelancing on the side, working evenings or weekends, or earning rental or overseas income alongside employment.
However, many people are caught out by how HMRC taxes a second job. Without understanding how the rules work, you could end up overpaying tax or needing to file a Self Assessment unexpectedly.
This guide explains how second job tax works in the UK, how much tax you’ll pay, and when you need to submit a Self Assessment tax return.
How Does Second Job Tax Work in the UK?
HMRC does not tax your jobs separately. Instead, all your income is combined to calculate how much tax you owe overall.
This includes income from:
- Your main employment
- A second or part-time job
- Freelance or self-employed work
- Rental income (UK or overseas)
- Overseas income (if UK-resident)
Your total income determines:
- Your tax band (20%, 40%, or 45%)
- Whether National Insurance applies
- Whether you must file a Self Assessment tax return
Your Personal Allowance and a Second Job
Most people receive a Personal Allowance of £12,570, meaning you don’t pay Income Tax on the first £12,570 you earn.
HMRC usually:
- Allocates your Personal Allowance to your main job
- Taxes income from your second job without any allowance
This is why second jobs are often taxed at 20% or more from the first pound.
Tax Rates on a Second Job (2024/25)
Once your Personal Allowance is used, income is taxed as follows:
- 20% Basic Rate: £12,571 – £50,270
- 40% Higher Rate: £50,271 – £125,140
- 45% Additional Rate: Over £125,140
Example:
- Main job salary: £35,000
- Second job income: £10,000
- Total income: £45,000
The second job income is taxed at 20%, because your total income remains in the basic rate band.
Why Is My Second Job Taxed at 20% (or More)?
Second jobs are often placed on a BR, D0, or D1 tax code, meaning:
- BR – taxed at 20%
- D0 – taxed at 40%
- D1 – taxed at 45%
This doesn’t mean HMRC is overcharging you — it’s a way of collecting tax correctly based on your total income.
If your total income increases during the year, HMRC may adjust your tax code automatically.
What If You Earn Less Than £12,570 Across Both Jobs?
If your combined income is below £12,570, you can ask HMRC to:
- Split your Personal Allowance between jobs
- Reduce or eliminate tax deducted from your second job
This can prevent unnecessary overpayment.
Do You Need to File a Self Assessment for a Second Job?
You may need to file a Self Assessment tax return if you:
- Earn more than £1,000 from self-employment
- Have untaxed income (freelance, rental, overseas income)
- Are a higher-rate taxpayer
- Earn over £100,000
- Are a non-resident landlord or expat
- Want to claim tax reliefs or refunds
Even if PAYE is deducted, Self Assessment is often required to true-up your tax position.
Second Job Tax for Non-Residents, Expats, and Landlords
Non-Resident Landlords
UK rental income is still taxable, even if you live abroad. If you also have UK employment income, both are considered when calculating tax.
Expats Moving In or Out of the UK
Residency status affects:
- What income is taxable
- Whether overseas income must be declared
- Whether Double Taxation Relief applies
These cases almost always require a Self Assessment tax return.
Common Mistakes People Make with Second Job Tax
- Assuming PAYE always gets it right
- Not declaring freelance or side income
- Ignoring tax code changes
- Forgetting National Insurance on second income
- Missing the Self Assessment deadline (31 January)
These mistakes often lead to unexpected tax bills or penalties.
