growstuff
For those above SPA, income from pensions could be exempted. People with private pensions paid NICs (but not tax) before the contributions were deducted. NICs are also calculated on gross income. However, as I've argued elsewhere, I think it's totally unfair that certain groups are effectively taxed at 2/3 of the rate of others. I think income and wealth rather than age should be the deciding factor. I agree with you DaisyAnne that a hypothecated healthcare tax (at a lower rate than NI) might work.
It would a new insurance for everyone. Everyone would pay less elsewhere. Surely the same income should be reflected by the same tax. Why should a pension income of, say £100,000 be untaxed when it comes to Health and Care. The Personal Allowance would still be there.
I don't understand your 2/3 comment. Could you expand on it for me?