In the UK we have the tax free allowances, but we start to lose them as we earn more. For instance, around £100k in earnings they start to tax your personal allowance so you are effectively taxed at 60%. You then move into 45% tax and then start to lose pension allowances at £250k.

First world problems, but these are all cliffs where it makes sense to keep your income down. Losing 20% off the top line will reduce your income by closer to 10% if my math is correct.

We have a problem in the UK with higher earners dropping out of the workforce partly because of the tax incentives. I personally choose not to work as an employee in the UK because I would be paying more than 50% in tax.