The UK had 91% tax from 1945 - 1963 https://www.wolterskluwer.com/en/expert-insights/whole-ball-of-tax-historical-income-tax-rates
Didn't know that!
But it’s not normally 90% of everything. It’s normally (for example): First 12K - no tax, next 13K - 20% tax next 50K - 40% tax next 50K - 50% tax anything above that 90% tax