UK Bonus Tax Calculator - Cash vs Pension

See exactly what you keep from your bonus — and what you could keep instead by salary-sacrificing into your pension. The tool models the 2026/27 income tax bands, NI, and the brutal £100k–£125k Personal Allowance taper trap.

Your bonus

Annual base salary (£)Bonus amount (£)Employer adds their 15% NI saving to my pensionWhen you sacrifice, your employer also saves 15% Class 1A NI. Many generous employers add some or all of that into your pension as a sweetener — ask payroll if yours does.

Enter your annual salary and bonus on the left to see the comparison.

Why bonuses feel taxed harder than they are

UK PAYE works cumulatively across the tax year. When a one-off bonus lands, the engine briefly treats your annualised income as much higher than it actually is, deducting more tax than your eventual annual rate. The over-deduction reverses out over the following months — but the cash hit in the bonus month feels harsh.

Salary-sacrifice-into-pension avoids the spike entirely. For higher-rate taxpayers, sacrificed bonus money avoids 40% tax and 2% NI; for taxpayers in the £100k–£125k zone, the saving rises to roughly 60% because the sacrifice also restores lost Personal Allowance.

Read the full bonus taxed too much guide for the maths and the salary-sacrifice mechanics, and the salary sacrifice deep dive for the broader strategy.

Disclaimer: PayslipIQ provides automated educational guidance based on the figures you supply. It is not regulated tax, financial or pension advice. We are not authorised by the Financial Conduct Authority. Pension contributions are long-term commitments; consult an FCA-regulated adviser before significant decisions.