(all figures approximate) Once you get to £100,000/year gross salary, the tax-free allowance starts to taper away. At £100,000/year, your tax free allowance is

(all figures approximate) Once you get to £100,000/year gross salary, the tax-free allowance starts to taper away. At £100,000/year, your tax free allowance is ~£12,000; at £125,000/year, your tax free allowance is £0. Suppose now you got a pay rise from £100,000 to £125,000. At £100,000, your take home pay was ~£66,500; at £125,000, your take home pay is ~£76,000. Your overall tax rate was ~33.5%, now ~39%. But comparing this year's payslips with last year's, you'll notice that of the £25,000 increase in the headline figure, ~£9,500 has actually made its way into your bank account. And 9500/25000=0.38. That's where the 62% figure comes from. In practice, since the max tax rate is 45%, and employee's NI is around 1% at that point, your overall tax rate never gets past 46%. (For example, suppose you earn £1m via PAYE: net salary is ~£541,000. Overall tax rate therefore 45.9%.) You can get approximate figures for this stuff out using https://listentotaxman.com/ https://listentotaxman.com/. If you want proper advice, you can pay an accountant.