Just take a look at the tax rates of 1978 Britain:
below £750 - rate of 25 per cent,
otherwise below £7,000 - basic rate of 34 per cent
The next £1,000 40 per cent.
The next £1,000 45 per cent.
The next £1,000 50 per cent.
The next £1,500 55 per cent.
The next £1,500 60 per cent.
The next £2,000 65 per cent.
The next £2,500 70 per cent.
The next £5,500 75 per cent.
The remainder 83 per cent.
That £7,000 is about $100,000 in 2023 money. The 55% bracket kicked in at about $140,000 in 2023 money.
There’s a reason why Joe wants ~80,000 more IRS people, the tax rates are going to go so high that millions of Americans will try to illegally avoid getting fleeced.
“That £7,000 is about $100,000 in 2023 money. The 55% bracket kicked in at about $140,000 in 2023 money.”
I believe that UK tax rates in 1978 were even more confiscatory than what you describe.
I plugged in £7,000 in 1978 into a CPI inflation calculator and got the following:
“Value of £7,000 from 1978 to 2023
£7,000 in 1978 is equivalent in purchasing power to about £51,381.33 today, an increase of £44,381.33 over 45 years. The pound had an average inflation rate of 4.53% per year between 1978 and today, producing a cumulative price increase of 634.02%.
This means that today’s prices are 7.34 times as high as average prices since 1978, according to the Office for National Statistics composite price index. A pound today only buys 13.624% of what it could buy back then.”
https://www.in2013dollars.com/uk/inflation/1978?amount=7000
Under the current exchange rate, £51,381.33 is equal to $63,669.53. That means that the 41978 UK 40% tax bracket would start at the equivalent of around $64,000 (not $100,000) today, and the 55% bracket would kick in at the equivalent of a little less than $91,000 (not $140,000) today. And the 75% bracket would start at less than $160,000!