Well the UK is at 40% too if you also include national insurance contributions, but both income tax and national insurance are calculated by employers and paid

Well the UK is at 40% too if you also include national insurance contributions, but both income tax and national insurance are calculated by employers and paid automatically out of your payslip (PAYE). This means most people never have to think about doing a tax return, and also means it’s harder to hide earnings for most people. There is then a process where people with more complex tax affairs then fill in a government questionnaire on a website which instantly calculates the tax rebate/payment required and adjusts your tax balance.