See what a second job costs in tax and National Insurance, why the BR tax code is not a penalty, and when PAYE under-collects.
A second job is usually taxed under a BR code, which takes basic rate from every pound of it. That looks punitive but it is not: while your combined income stays within basic rate you pay exactly the same income tax as you would earning the same total in one job. National Insurance is where the two genuinely differ, because it is worked out separately for each employment.
Enter both salaries. The second job is taxed without a Personal Allowance, and National Insurance is charged on each job separately.
The second job is taxed on a BR code, which gives it no Personal Allowance of its own: the allowance is set against the main job. National Insurance is normally charged separately on each employment, so each job gets its own threshold. That is worth £516 a year here, and unlike the tax it is not collected back later. It does not apply where both jobs are with the same employer, or with employers connected to each other: those earnings are added together and there is one threshold between them. Income Tax is the part to watch. Across the two jobs PAYE collects £946 less than the same total would pay in one job, because a flat second-job code cannot see the band the two of them reach together. That is not money saved. HMRC collects it later, by changing a tax code or through Self Assessment. All of that assumes the BR code above. Where the main job alone has already used up the basic-rate band, HMRC puts the second job on a higher-rate code instead — on D0 here, PAYE would collect £1,054 too much rather than too little. Check which code the second payslip actually shows. The figures use England, Wales and Northern Ireland rates for the current tax year. Scottish rates change the Income Tax half of them. This compares PAYE deductions across two jobs against the same total in one job. It does not decide your tax code, and it cannot see what HMRC has already allocated between your employments.
Each row runs the same engine twice, once per employment, and compares it against earning the identical total in a single job. The second job is on a BR code throughout.
| Main job + second job | Take-home across both | National Insurance difference | Income tax deferred |
|---|---|---|---|
| £20k + £5k | £21,920 | £400 | none |
| £25k + £8k | £27,920 | £640 | none |
| £30k + £8k | £31,520 | £640 | none |
| £38k + £10k | £38,880 | £800 | none |
| £45k + £10k | £43,920 | £516 | £946 |
| £60k + £20k | £60,763 | -£194 | £4,000 |
The National Insurance column is a real difference, usually in your favour, because each employment is normally assessed against its own thresholds. It turns negative once a single job would have passed the point where the employee rate drops, which is what the last row shows. It does not apply at all where both jobs are with the same employer or with connected employers, because those earnings are added together.
The deferred column is not a saving: it is what a basic rate code fails to collect once combined income reaches higher rate, and HMRC reclaims it later. It assumes that basic rate code throughout. On the rows where the main job alone already uses the basic-rate band, HMRC would use a higher-rate code instead and the deferred figure would be smaller or nil.
| Tax/source year | 2026/27 |
|---|---|
| Region | England/Wales/Northern Ireland |
| Tax code basis | 1257L where the page uses PAYE defaults |
| Pension basis | No pension deduction unless this example says otherwise |
| Student loan basis | No student loan unless selected in this example |
| What is not decided here | PayBreakdown does not decide payroll correctness, lender approval, benefit entitlement or employer compliance, and does not give regulated financial, mortgage, debt, tax, payroll or legal advice. |
|---|
BR means all income from that job is taxed at the basic rate, because your Personal Allowance is already being used by your main job. Applying it once, in one place, is the point.
This is the part that genuinely changes your take-home. Each employer runs National Insurance against its own thresholds rather than against your combined earnings.
A basic rate code on the second job cannot know your combined income. Once the total crosses the higher rate threshold, the second job is under-taxed during the year and HMRC reclaims the difference afterwards.
Change any figure above and the result moves with it. A payslip can differ from any calculator because payroll works pay period by pay period, so a tax-code change, a bonus, arrears or a refund can land in one month and not the next. See how each deduction is worked out.
Not while your combined income stays within basic rate. A BR code taxes the whole second job at 20% because your Personal Allowance is already used by the first job, and that comes to the same income tax you would pay earning the same total in one job.
BR means all income from that job is taxed at the basic rate. It is applied because your tax-free Personal Allowance has already been allocated to your main employment, so there is none left to set against the second job.
You pay it separately on each job, which is not the same as paying twice. Each employment is assessed against its own thresholds, so a second job below the threshold pays no National Insurance at all, and two jobs on the same total often pay less than one job would.
You can, if your combined income crosses the higher rate threshold while the second job is still on a basic rate code. PAYE then collects too little during the year and HMRC reclaims the difference, usually through a tax calculation or a changed code.
Last updated 2026-08-27. Checked by Sean Elsmore. Rates last checked against GOV.UK on 2026-08-07. Estimates are for planning and should be checked against official records where the decision matters.