How UK Bonuses Are Taxed Through PAYE

It is the moment every hardworking employee looks forward to: bonus month. You have hit your targets, the company has had a great year, and you are expecting a significant lump sum. But when you finally open your payslip, the excitement quickly turns to disappointment and confusion. Why is the take-home amount so low? Why did you pay 40% tax when you are usually a Basic Rate taxpayer? This phenomenon is incredibly common, and understanding why the PAYE system "spikes" your tax is essential for managing your finances and ensuring you keep as much of your bonus as possible.

How the PAYE System Views Your Pay

PAYE uses your tax code and the payroll period to determine how much Income Tax to deduct. With a normal cumulative code, payroll considers taxable pay and tax already deducted in the tax year. A Week 1 or Month 1 code instead treats each period separately. A bonus increases taxable pay in the payment period, so more of the cumulative total may fall into a higher band even though payroll does not simply multiply that month's pay by 12.

How cumulative PAYE handles a bonus

Consider a regular salary of £36,000 a year, or £3,000 gross per month, followed by a £5,000 performance bonus in March. Gross pay for that month is £8,000, while cumulative PAYE also considers taxable pay and tax already recorded earlier in the tax year.

That £8,000 payment is added to taxable pay for the year. Depending on the tax code, pay date and previous pay and tax, some of the bonus may use the basic-rate band available to that point and the rest may be taxed at a higher rate. The deduction can therefore be much larger than in a normal month without meaning that the whole bonus has a single special tax rate.

National Insurance: A Different Story

Unlike cumulative Income Tax, National Insurance is normally calculated for each pay period. For 2026/27, a monthly paid category A employee pays 8% on earnings above £1,048 and up to £4,189, then 2% above £4,189.

This is the silver lining of a large bonus. Because National Insurance is non-cumulative, a huge bonus in a single month will push a significant portion of your earnings above the £4,189 Upper Earnings Limit. This means a large chunk of your bonus is only subjected to 2% National Insurance, rather than the standard 8%. This quirk in the system actually saves you money compared to receiving that same bonus spread out over 12 months.

Will I Get the Tax Back?

A large deduction is not automatically an overpayment. With a cumulative tax code, later payroll calculations use updated year-to-date pay and tax and can correct an earlier excess during the same tax year. If too much tax remains after the year ends, HMRC may reconcile it, but the outcome depends on your total taxable income and tax code.

If a possible overpayment remains after the tax year, HMRC may reconcile the record and issue a P800. A calculation does not always mean a refund is due, and any repayment method depends on HMRC's instructions and the information held on your record.

Using bonus sacrifice

If an employer offers a valid bonus-sacrifice arrangement, agreeing the sacrifice before entitlement can redirect some bonus into a workplace pension and reduce current taxable and National Insurance earnings. Pension limits, scheme rules and later taxation of pension benefits still apply; it is not equivalent to receiving the same amount as tax-free cash.

Your employer may also save employer National Insurance when a valid bonus-sacrifice arrangement reduces cash pay. Whether any of that saving is added to your pension is an employer policy decision, so check the scheme rules before acting.