Second Job Tax Calculator: Payslips vs What You Really Owe
Two payslips can each look correct and still add up to the wrong amount of tax. Each employer only sees its own pay, so your main job gives you the full allowance while the second job guesses at a rate, and nobody checks the total until HMRC does after 5 April. By then the gap can be a refund of several hundred pounds or a bill of a couple of thousand.
Second Job Tax Calculator 2026/27
See what each job deducts, what you really owe on both together, and whether a refund or tax bill is coming.
Main job
Second job
Use the codes on your payslips. Enter pay after any salary sacrifice. Scottish codes such as SBR or SD0 are read automatically.
Take-home from both jobs
Income Tax you really owe
National Insurance
Second job: you keep
of every £100 earned
What each payslip deducts
| Yearly | Main job | Second job | Both |
|---|
Assumes steady pay all year and no other income. Payroll figures follow each tax code on a cumulative basis. Your real tax is worked out on both jobs together, which is what HMRC checks after 5 April.
This second job tax calculator puts both jobs side by side, shows what each payslip deducts, works out the Income Tax you really owe on the combined total, and tells you which codes HMRC would normally give each job.
How to use it
- Enter the pay for each job before tax, after any salary sacrifice.
- Copy the tax code from each payslip. If you do not know the second job's code yet, tap Not sure and the calculator fills in the code HMRC would normally use.
- Pick Scotland if you are a Scottish taxpayer. Codes such as SBR, SD0 and SD1 are read with Scottish rates.
- Add your student loan plan if you have one, then calculate.
Using the second job tax calculator with monthly pay
Shift work and part-time jobs are often easier to think about by the month. Switch Pay entered as to Monthly or Weekly and type the usual amount for one period. The calculator turns it into a yearly figure, works out the tax, then shows the result per month as well as per year.
Worked examples from the second job tax calculator
These five cases cover the situations people ask about most, from codes that work perfectly to the classic 1257L mistake.
Second job tax calculator examples, 2026/27
| Main + second job | Codes | Payslips take | Tax owed | Result |
|---|---|---|---|---|
| £30k + £8k | 1257L, BR | £5,086 | £5,086 | Correct |
| £45k + £15k | 1257L, BR | £9,486 | £11,432 | −£1,946 |
| £8k + £10k | 1257L, BR | £2,000 | £1,086 | +£914 |
| £30k + £12k | 1257L, 1257L | £3,486 | £5,886 | −£2,400 |
| £30k + £12kScotland | S1257L, SBR | £5,851 | £5,971 | −£120 |
Income Tax only, yearly figures. A minus result is tax still to pay, a plus result is a refund. The Scottish case needs SD0 on the second job because the main job already reaches the 21% intermediate band.
The second row is the one that catches people out. A £15,000 second job on BR is taxed at 20%, yet £9,730 of it sits above the £50,270 higher rate threshold once both salaries are added together. The payslips are short by £1,946, and HMRC will ask for it back.
Why your payslips and your real tax can differ
PAYE works job by job. Your main employer applies your Personal Allowance and the normal tax bands to its own pay. Your second employer applies whatever code HMRC gave it, usually BR, which taxes every pound at 20% because the allowance is already being used elsewhere. Neither employer knows what the other pays you.
Your actual tax bill is worked out on both incomes together. When the second job pushes your total into a higher band, BR takes too little. When your main job pays less than £12,570, part of your allowance goes unused and BR takes too much. The second job tax calculator shows both figures, and the difference is what HMRC will collect through a code change or a P800 calculation, or refund to you. Our second job tax guide explains each code and when HMRC uses it.
The 1257L on both jobs mistake
If you tick the wrong box on the second employer's starter checklist, it may give you 1257L as well, so you get the tax-free allowance twice. On £30,000 plus £12,000, that leaves £2,400 untaxed by payroll. The money feels like extra pay until HMRC catches up. Our guide to the emergency tax code explains how the starter checklist statements decide which code a new job uses.
How much tax do you pay with two jobs?
There is no special rate for a second job. You have one Personal Allowance and one set of tax bands for all your work combined, and the second job is taxed at whatever rate your combined income reaches. For most people that means 20% on every pound of the second job, because the allowance is used up by the main one. If your total goes above £50,270, the part over that line is taxed at 40%, or 42% in Scotland above £43,662.
The "you keep" figure in the results shows the real effect. It takes the extra Income Tax, National Insurance and student loan caused by the second job and tells you how much of each £100 you earn there ends up in your pocket.
National Insurance and student loans on two jobs
National Insurance is not combined the way Income Tax is. Each job is checked against its own £12,570 threshold, so a second job paying under £12,570 a year usually has no employee NI at all. With £30,000 and £12,000, you pay £960 less NI than someone earning £42,000 from one employer.
It can work the other way at higher pay. Two jobs of £50,000 each are both charged 8% up to £50,270, which comes to £1,978.20 more than a single £100,000 salary. HMRC can refund NI paid above the yearly maximum after the tax year ends, or you can ask to defer it in advance.
Student loans follow the same per-job rule through payroll. With Plan 2 on £45,000 and £15,000, payroll takes £1,405.35, because the second job is below the £29,385 threshold. If you fill in a Self Assessment return for any reason, repayments are worked out on total income instead, and the bill rises to £2,755.35.
What the calculator does not cover
Scotland, Wales and Northern Ireland
The second job tax calculator is built for two steady PAYE incomes, so a few situations are left out.
- Self-employed side income. Profits are taxed through Self Assessment, and the first £1,000 of trading income can be covered by the trading allowance.
- Irregular pay, bonuses or months with no pay, which change how PAYE spreads the allowance.
- Emergency codes marked W1, M1 or X, which ignore pay earlier in the year.
- Benefits in kind, savings interest, dividends and the High Income Child Benefit Charge.
A workplace or private pension paid through PAYE is taxed exactly like a second job, so you can enter it in the second job box.
Frequently Asked Questions
Rules and rates used
- GOV.UK: How tax works if you have more than one job
- GOV.UK: What your tax code means (BR, D0, SBR, SD0 to SD3)
- GOV.UK: Rates and thresholds for employers 2026 to 2027
- GOV.UK: Check your Income Tax for the current year
Checked against 2026/27 rules. See how we calculate for the method behind our tools.