How to calculate tax on a second job
Your allowances are usually used up by your main job, so a second job is often taxed from the first pound at your marginal rate. The right way to work it out is to add both incomes together and tax the total, rather than treating the second job in isolation.
The rule
Second-job take-home = second-job pay − (second-job pay × combined marginal tax + contribution rate)
Do it automatically — Second-job taxStep by step
- 1Add your main salary and expected second-job income to get total earnings.
- 2Work out total tax on the combined figure using the bands.
- 3Subtract the tax you already pay on the main job — the difference is the tax on the second job.
- 4Add social contributions, which are usually charged separately per employment.
What trips people up
- • A BR or D0 tax code on the second job means no allowance is applied there — that is normally correct, not an error.
- • Self-employed side income is not taxed at source; set money aside and file a return.
Common questions
Do I pay more tax overall for having two jobs?
No — the total is the same as if one employer paid you the combined amount.
Should I split my allowance between jobs?
Only if both are steady; otherwise you risk under-paying at one and owing at year-end.
Skip the maths
Estimate net pay on a second job stacked on top of your main salary.
Open the take-home from a side role tool