There's no "high income cap" on NICs. There's a lower rate for employees above a certain level but this is offset by a higher income tax rate which occurs at th

There's no "high income cap" on NICs. There's a lower rate for employees above a certain level but this is offset by a higher income tax rate which occurs at the same pay level so that the combined rate of tax and NICs goes 0%-12%-32%-42% for people who are paid evenly throughout the year (it then gets a bit weird above £100k because the marginal rates become 62% then back to 42% then 47% above £150k/year). Employers pay 13.8% of all earnings above the "secondary threshold" with no reduction. (There's a good case for effectively removing that 12% bit by moving up the point where you start to pay NICs to align with the personal allowance and for assessing NICs annually instead of weekly/monthly. There are also complicating factors like under 21s partly and over state pension age fully not paying NICs too). I've also never heard a politician say that "mass immigration" is needed because of nurses, and indeed it would be not be most people's idea of "mass immigration" even if every single nurse working in the NHS were an immigrant - there are around 300,000 nurses working in the NHS.