I don’t understand your logic? It sounds like you’re saying you changed jobs for less money so that your marginal tax rate would be lower even though your net income would be lower. In theory you could also change jobs to something that pays £125k where your marginal tax rate would be back down to 40%, though obviously you’d need to find such a job. You specifically wrote ‘marginal’ so I don’t think you’re confused between marginal and effective tax rates so are you suggesting that the 60p rate did not provide sufficient incentives for you to try to get paid more? That would maybe make sense but I think it can also be useful to think of pay raises on a logarithmic scale rather than a linear one (as in an equal amount of raise-worthiness would be expected to lead to a proportionally larger raise in absolute terms if your starting pay is higher), which would mean an x% raise at a higher marginal tax rate may still be worth it if your starting pay is higher. But then another common model is log utility for money which cancels out that effect.

It’s fair enough if you want to work at the startup but this seems like a strange rationalisation. I agree that the 60% marginal rate from the personal allowance reduction is kinda silly.