Talking to doctor friends, there is also something weird going on where you can end up paying more tax then you take home in salary at the end of the year. I know this first hand from someone who had to use savings to pay their tax bill so essentially ended up paying to work that year.
It has something to do with having to pay capital gains tax on the gains in your pension funds, but I'm not sure about the details. Another friend has a colleague in his department who is going on a six month sabbatical to avoid the same situation.
Nothing to do with capital gains.
You're (usually) allowed to contribute up to 40K into your pension per year and not pay any income tax on that money. Over that amount and any extra you still have to pay the income tax (I'm simplifying the situation slightly)
If you're in a defined benefit pension scheme, the amount you pay into the pension is calculated by taking the difference between the pension you would have got at the end of the year and the start of the year and multiplying it by (I think) 20x. So if your expected pension goes up by 2K then that's 40K contributed. Senior consultants might be earning (take home before tax) 160K, on a 1/60th scheme. So each extra year of work will see their final salary go up by 160/60 or 2.6K so the equivalent of 50K into their pension.
So that 50K is added to their income (now 210K)
It's now been changed but a few years ago, anyone earning over 150K saw the amount that could be paid into their pension being reduced by 1GBP per 2GBP over. So someone earning 210K would only get a pension allowance of 10K (the minimum at the time).
So our consultant pays 45% tax on 40K of pension contributions.
So what, you say, that's only 18K - but they didn't get the 50K that was added to their notional pension contribution, so they have to pay it from the 160K of earnings - and they end up poorer as a result.
Because of the really, stupidly, complex rules around this pension taper, it became critical for people in this situation to avoid earning over 140K to avoid any risk of this tax whammy. So we got these senior consultants refusing weekend work, overtime and basically "working to rule" not because they weren't prepared to do more work but because they couldn't afford to do more work because their take home pay would reduce even if their total remuneration would go up.
The limit has now been changed, I'm not sure of the exact numbers but somewhere around 200K - enough that UK consultant doctors shouldn't be caught by this tax trap.
Because of the really stupid way this tax regime was created, it was actually possible to have a 1.4 million percent marginal tax rate - someone earning 1GBP more, in the worst possible case, could pay 14K tax more. This was related to that 140K limit I mentioned - be below (excluding pensions) and the taper regime didn't apply, go over it, by even 1gbp and now this taper regime does apply and your income is increased by the amount of your pension contributions.