Second Job Tax Calculator, 2026/27

How this is calculated

This calculator computes the total income tax due on your main salary alone, then again on your main salary plus the second income combined, and treats the difference as the tax attributable to the second job. This mirrors how HMRC actually taxes a second PAYE job, using a BR, D0 or D1 tax code that applies basic, higher or additional rate from the first pound, because the personal allowance is already assumed to be used against the main employment.

Where the combined income pushes part of it into a higher band, the extra tax rate on the second job can look much higher than expected, even though the overall calculation is exactly the same total liability as if it were one combined salary.

If your second job's income tax code is wrong, for example still carrying a personal allowance that should sit against your main job, HMRC will eventually reconcile this and either bill you or refund you the difference.

PAYE coding for multiple jobs

By default HMRC allocates your full personal allowance to whichever job it considers your main employment, usually the one that started first or pays the most, and taxes any other job at a flat rate with no allowance at all. You can ask HMRC to split the allowance across two jobs if that suits your circumstances better, though this rarely changes the total tax due over the year.

Self-employed side income is not taxed through PAYE at all; it is reported on a self-assessment return and combined with employment income there instead.

Why a second job can feel like poor value

Because the personal allowance is already used, every pound of a second job is typically taxed at 20% and full National Insurance from the outset, and if it tips total income over £50,270 the marginal rate rises to 40%. This is the same total tax as if the income had all come from one employer, but it can be surprising to see so little in the second payslip.

For side income run through a limited company instead of employment, comparing salary, dividends and retaining profit in the company can sometimes be more efficient, and is worth a separate calculation.

Why is my second job taxed at a flat rate with no allowance?

HMRC assumes your personal allowance is already used against your main job, so a second PAYE job is usually coded BR, D0 or D1, taxing all of it at basic, higher or additional rate from the first pound.

Can I split my personal allowance between two jobs?

Yes, you can ask HMRC to allocate part of your personal allowance to each job, which changes how tax is deducted month by month but does not change the total tax due over the year.

Does National Insurance work the same way across two jobs?

No, National Insurance is generally assessed separately for each job against its own threshold, so a modest second job may attract less National Insurance proportionally than income tax.

Is side income from self-employment treated the same as a second job?

No, self-employed income is not taxed through PAYE. It is reported on a self-assessment return, combined with your employment income for income tax purposes, with Class 2 and 4 National Insurance calculated separately.