Still doesn't matter if something is "heavily taxed" because regardless of how much tax, you'll never own more in taxes than you made. So if you got a 10,000 bonus and it was heavily taxed at 60 percent, you don't somehow have to pay like 15,000 in taxes or something on it. You pay 60% of 10,000, leaving you with 4,000 left over. This is typically done before you even see the money, if not ensure that you keep funds aside to pay for the tax.

Also looking briefly at Japan, it appears that their income tax is a bracket based system similar to the US. So again, even if you go up a bracket, you'll never own more taxes than you make. Honestly, people need to stop thinking in brackets when it comes to taxes, all you need to worry about is your "effective tax rate." That's it, you don't need to worry that your income pushed you into a 29% tax bracket or whatever. All that matters is your effective tax rate is 24.2% or whatever. You'll never own more money because you "moved" into a higher bracket, because that's not how that works.