Tax levels for everyone:
Personal Allowance Up to £11,500 0%
Basic rate £11,501 to £45,000 20%
Higher rate £45,001 to £150,000 40%
Additional rate over £150,000 45%
Higher earners don't get the personal allowance though.
National insurance rates actually drop for high earnings over a threshold.
£113 to £157 a week (£490 to £680 a month) and you don't contribute.
£157.01 to £866 a week (£680.01 to £3,750 a month) and you pay 12% on those earnings.
Then anything over £866 a week (£3,750 a month) is flat rate charged at 2%, because it's supposed to be national insurance, and your contributions have been met from the levels below.
In other words, as a percentage of overall income a high earner pays less of their salary towards national insurance than the average bod. Higher amount overall, of course... but a lower percentage.
Not sure how that gets to a 63% figure, really. Unless you're factoring in the employer's contributions to NI as well, which is, bluntly, disingenuous to the nth degree.