If you want to know the tax on a £120,000 salary in the UK, the answer is not one simple percentage. Both the tax bands and National Insurance matter.
Only the top slice of income is taxed at the highest rate you reach. That is why rough percentage estimates often mislead people.
Compare gross salary, estimated net pay and the effect of pension changes rather than focusing on a single headline rate.
Run your own scenario and compare one or two alternatives. That usually reveals the real decision much faster than generic advice.