Re: Well paid devs
That's very roughly rough. It's no tax up to 12.5K. Then for the amount between 12.5K and 50K it's 20% (still zero on the first 12.k).
Then on the earnings above 50K and below 150k it's 45%. So if you earn 55K, you only pay 40% on 5K.
Plus NI and any pension contribution that is topped up by employer.