Tax on bonus and commission can make a record month feel punishing. Here is why a spike month is taxed harder under PAYE, and how to legally keep more.
Payday should feel good, especially the one after a record commission or bonus month. Then the money lands, you check the figure, and it is hundreds of pounds lighter than the sum in your head. Welcome to the tax on bonus and commission shock: the moment a sales rep or commission earner decides payroll must have made a mistake.
I have watched friends in sales stare at a payslip after their best month of the year and assume something is broken. Usually nothing is. The deduction is real, some of it you will get back, and some of it you will not. Here is exactly what is happening, why it happens, and the one move that genuinely keeps more of your commission in your pocket.
A bonus or commission is taxed like the rest of your pay, but because PAYE assumes your income is smooth, a single spike month gets front-loaded with tax that either evens out later or, if the spike tips you into a higher band, stays gone for good.
There is no separate, harsher “commission tax rate” in the UK. That is the first myth to drop. Your commission goes through the same income tax bands and the same National Insurance as your salary. What changes is the timing and the band you land in.
Two systems run over your pay at once, and they behave differently when a big month arrives.
Income tax is cumulative. Your £12,570 personal allowance for 2026/27 is sliced across the year, roughly £1,047.50 a month, and protected from tax. Everything above that is taxed at 20 per cent up to £50,270, then 40 per cent up to £125,140, then 45 per cent. Because it is cumulative, payroll looks at your year-to-date pay every time it runs.
National Insurance is not cumulative for most employees. It is worked out fresh each pay period: 8 per cent on monthly earnings between £1,048 and £4,189, then 2 per cent on anything above £4,189.
Take a rep on a £42,000 base, so £3,500 a month, who earns an £8,000 commission in one month.
A normal month at £3,500:
The commission month at £11,500:
Notice the National Insurance only rose from about £196 to about £398, not eight times higher, because everything above £4,189 in the month is charged at just 2 per cent. On National Insurance, a lumpy month is often cheaper than the same money spread out. That part of the shock works in your favour.
Income tax is where the sting sits, and it depends entirely on where your yearly total lands.
Same commission, three very different outcomes.
If you stay in basic rate, it is pure timing. Base £42,000 plus £8,000 commission is £50,000 for the year, still under £50,270. Every pound is taxed at 20 per cent over the year. Your commission-month payslip still looks brutal, because cumulative PAYE reacts sharply to the sudden jump, but it corrects across the following months. Nothing is genuinely lost.
If the payday tips you over £50,270, some tax is real and permanent. Base £46,000 plus £8,000 commission is £54,000. Now £3,730 sits above the higher-rate threshold and is taxed at 40 per cent instead of 20. That is £746 of extra tax that does not come back, because the commission genuinely pushed part of your year into the 40 per cent band.
If you are on an emergency code, it is the worst version. A W1 or M1 code is non-cumulative, so payroll treats that single £11,500 month as if you earn it every month. It annualises the spike to £138,000, taxes the month as though you are a six-figure earner, and drags in 40 and even 45 per cent. You reclaim the excess, but it can take until later payslips or the end of the tax year, and in the meantime you are out of pocket by a serious amount. New starters and anyone whose employer has not processed a recent P45 are the most likely to be caught by this. If you see W1 or M1 next to your tax code after a big month, that is your answer.
Then there is the harshest trap of all. A rep on a £95,000 base who lands a £20,000 commission reaches £115,000. Between £100,000 and £125,140 you lose £1 of personal allowance for every £2 you earn, which stacks an extra hidden charge on top of the 40 per cent rate. The slice between £100,000 and £115,000 is effectively taxed at 60 per cent, so £9,000 of a £15,000 commission slice disappears in tax. This is the commission shock at its most painful, and it is also the most avoidable.
Four moves, in order of impact.
Check your tax code first. If you see W1 or M1, you are on a non-cumulative code and almost certainly over-taxed on the spike. Check it on the HMRC app or your Personal Tax Account. On a normal cumulative code, the system reconciles itself, which is far less frightening than it feels in the moment.
Use bonus sacrifice into your pension. This is the single most powerful lever. Ask payroll to divert some or all of the commission straight into your pension before tax touches it. If the payment tips you over £50,270, sacrificing the slice above the threshold turns money that would be taxed at 40 per cent and often lost into pension savings that are yours. If it pushes you into the £100,000 taper, sacrificing back under £100,000 rescues personal allowance worth an effective 60 per cent. Search bonus sacrifice and salary sacrifice pension if you want to read more before you ask.
Know what reconciles and what does not. Income tax over-charged purely by timing comes back automatically over the year. National Insurance does not reconcile for most employees, but as we saw, a lump usually costs less National Insurance, not more, so that is rarely the problem.
Spread the income if you have any control. Employees rarely get to choose when commission is paid, but if you invoice for any of it, smoothing payments across months keeps you under the band thresholds. It is worth asking your manager whether a large one-off can be split across two pay runs.
Very little changed in the rules, and that is exactly the problem. The personal allowance is still £12,570 and frozen until April 2028. The higher-rate threshold is still £50,270, and the additional rate still starts at £125,140. The £100,000 personal allowance taper is unchanged, so the effective 60 per cent band between £100,000 and £125,140 is still there waiting. National Insurance is still 8 per cent and 2 per cent for employees.
Because every threshold is frozen while pay and commissions keep rising, more earners are quietly tipped into the 40 and 60 per cent bands each year. The mechanism has not moved, but fiscal drag means the tax on bonus and commission shock catches more people every tax year.
If you want to see the damage before it hits your account, NetPay lets you drop in your base pay plus a commission month and shows your take-home in full, including income tax, National Insurance, pension, and salary sacrifice. Free to download.
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No. Commission is taxed at exactly the same rates as salary. It only feels higher because PAYE front-loads the tax on a spike month, and because a big payday can push part of your income into the 40 per cent band. If you stay within basic rate for the year, the extra deduction usually evens out through later payslips.
Most likely cumulative PAYE reacting to the sudden jump in your pay, or an emergency W1 or M1 tax code annualising the spike as if you earn that every month. Check your code on the HMRC app. If it is a cumulative code and your annual income stays in basic rate, the over-deduction comes back to you later in the year.
The most effective legal route is bonus sacrifice, asking payroll to pay some or all of it into your pension before tax. This is especially powerful if the payment tips you over £50,270 or into the £100,000 personal allowance taper, where the effective tax rate reaches 40 or 60 per cent.
Yes, if it was over-deducted by timing or a W1 or M1 code and your annual income does not actually reach those higher bands. HMRC reconciles income tax across the year, usually through later payslips or after the tax year ends. National Insurance is not reconciled the same way for most employees.
Want to see your actual take-home pay?
NetPay UK works out your real net pay after tax, NI, pension and salary sacrifice, for hourly, shift and variable-income workers. Free to download.
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A note on financial advice: NetPay UK calculates take-home pay based on official HMRC tax rules. This article reflects rules in force at the time of publication (12 July 2026). Tax rules change. For complex situations, consult a qualified UK accountant or visit gov.uk/income-tax.
