Second job tax calculator
Two jobs, one tax-free allowance. This shows your combined take-home, how the allowance splits, and the National Insurance rule that works in your favour.
How two jobs are taxed
Income tax looks at your total income, not each job on its own. Your personal allowance (the first £12,570, tax-free) is normally applied to your main job through your 1257L code. That leaves nothing tax-free for the second job, so it is taxed from the first pound at whatever rate your combined income reaches. It is not a penalty, although it can look like one on the payslip.
National Insurance is different. It is worked out per job, and each job gets its own threshold. That means two jobs of £19,000 pay less NI than one job of £38,000. This tool shows the saving on the right.
Worked example
On a £30,000 main job and an £8,000 second job, your combined income is £38,000, still inside the 20% band. The second job is taxed at 20% with no allowance, so of that £8,000 you keep about £6,400. Because NI is split across both jobs, you also save about £640 in NI compared with earning £38,000 in a single job.
Common questions
Is my second job taxed more?
Not at a special rate. Your tax-free personal allowance is usually all used by your main job, so the second job is taxed from the first pound at your marginal rate (20%, 40% or 45%). It can feel like more because there is no tax-free slice left for it.
How much tax do I pay on a second job?
Whatever rate your combined income reaches, applied from the first pound of the second job. If both jobs together stay under £50,270 the second job is taxed at 20%. Once the total crosses that line the part above is taxed at 40%. National Insurance is charged separately on each job, at 8% on that job’s earnings above £12,570, so a small second job can carry income tax but no National Insurance at all.
Why is my second job on a BR tax code?
BR means Basic Rate: every pound is taxed at 20% with no allowance, because the allowance sits on your main job. If your combined income is under the higher-rate threshold that is correct. If you earn more, some of the second job should be at 40%.
How much can I earn in a second job before paying tax?
Nothing, if your main job already uses the whole £12,570 personal allowance, which it does on any salary above that figure. The allowance belongs to you rather than to a job, and it is normally attached to one employment through the 1257L code. If your main job pays less than £12,570 you can ask HMRC to move the unused part to the second job, so some of that income becomes tax-free too.
Can I split my personal allowance between two jobs?
Yes. HMRC can divide the allowance across both employments and issue a code to each, which suits two steady part-time jobs of similar size. It is worth doing when the main job does not use the full allowance, because otherwise part of it goes unused all year and only comes back after the tax year ends. You arrange it through your Personal Tax Account or by phoning HMRC, and it takes effect through new codes sent to both employers.
Do I pay National Insurance on both jobs?
Yes, but separately. Each job has its own NI threshold, so you often pay less NI across two jobs than you would earning the same total in one job. This tool shows that saving.
Do I need to tell HMRC about a second job?
You do not have to contact HMRC yourself for a second PAYE job. Your new employer asks you to complete a starter checklist, and ticking the statement that says you have another job tells HMRC to issue a BR code. A self-employed sideline is different: that income is not covered by PAYE, so it goes on a Self Assessment return once it passes the £1,000 trading allowance.
Will my main employer know I have a second job?
Not from HMRC. Tax codes are issued to each employer separately and carry no detail about your other income, so the second employer sees only a BR or similar code. Your contract is a different matter: some contain a clause requiring you to declare other work, particularly where there is a conflict of interest or a limit on total working hours.
Why do I owe tax at the end of the year on a second job?
A BR code assumes all of that income belongs in the 20% band. If your two jobs together push you over £50,270, part of the second job should have been taxed at 40% and was not, so an underpayment builds up. HMRC usually collects it by adjusting your code for the following year rather than sending a bill. Entering both salaries above shows the correct combined tax before the shortfall builds.