It ended 51 years ago in 1972, but there was indeed a top rate of income tax called "super-tax" or "surtax" (only for very high earners) of 90% for a few decades:
"The highest rate of income tax peaked in the Second World War at 99.25%. It was then slightly reduced and was around 90% through the 1950s and 60s.[citation needed]
In 1971 the top rate of income tax on earned income was cut to 75%. A surcharge of 15% kept the top rate on investment income at 90%. In 1974 the cut was partly reversed and the top rate on earned income was raised to 83%. With the investment income surcharge this raised the top rate on investment income to 98%, the highest permanent rate since the war.[14] This applied to incomes over £20,000 (£221,741 as of 2021).
The Government of Margaret Thatcher, who favoured taxation on consumption, reduced personal income tax rates during the 1980s in favour of indirect taxation. In the first budget after her election victory in 1979, the top rate was reduced from 83% to 60% and the basic rate from 33% to 30%."
According to the history linked below, the super-tax/surtax was started in 1909, taxed only the top 0.05% of earners, and caused a constitutional crises as the budget was rejected by the House of Lords:
getwiththeprog|2 years ago
jlokier|2 years ago
https://en.wikipedia.org/wiki/History_of_taxation_in_the_Uni...
"The highest rate of income tax peaked in the Second World War at 99.25%. It was then slightly reduced and was around 90% through the 1950s and 60s.[citation needed]
In 1971 the top rate of income tax on earned income was cut to 75%. A surcharge of 15% kept the top rate on investment income at 90%. In 1974 the cut was partly reversed and the top rate on earned income was raised to 83%. With the investment income surcharge this raised the top rate on investment income to 98%, the highest permanent rate since the war.[14] This applied to incomes over £20,000 (£221,741 as of 2021).
The Government of Margaret Thatcher, who favoured taxation on consumption, reduced personal income tax rates during the 1980s in favour of indirect taxation. In the first budget after her election victory in 1979, the top rate was reduced from 83% to 60% and the basic rate from 33% to 30%."
According to the history linked below, the super-tax/surtax was started in 1909, taxed only the top 0.05% of earners, and caused a constitutional crises as the budget was rejected by the House of Lords:
https://www.nuff.ox.ac.uk/Economics/History/Paper43/43atkins...