Pension being paid out, is, as you say, taxed as income, are you suggestion the dividends and/or Capital Gains which are funding that payout should also add to the individuals tax liability?
Pension being paid into a scheme is not (generally speaking) taxed.
Not really suggesting anything. However broadly speaking, schemes that pay people via something other than a "salary" captured by income tax is an issue, when that other option accesses a much lower tax burden than someone else contributing the same to the economy.
Already, clearly, a small percentage of earners pay a high percentage of income tax - top 10% of incomes account for 60% of income tax more or less. So firstly there's a big incentive for high erarners to avoid this and secondly quite a lot of potential gain for government to close some loopholes. Just ignore the Daily Mail spouting off about disgruntled billionaires who don't pay it either way walking off in a huff to live in the Cayman Islands. That's not data.
I don't think pensions fall into the same category, although no doubt there are debates going on in Whitehall as we speak about how they should be taxed going in and coming out. I'm starting to think this chancellor is stupid enough to screw over the current working generation both in terms of retirement age and multiple tax filters on the money they need to avoid taking state benefits when they are old.