[sokoloff]

(It looks like it does/could.) I'd much rather file taxes than give the details down to the penny of my prior pay from employer 1 to my new employer 2 (which is what I think the P45 system does).

But that probably reflects more my own stance on personal and financial privacy than on anything fundamentally negative about the practical value of preserving that privacy.

[nsteel]

And in the case where you don't/can't provide a P45 they take an "emergency" high rate of tax instead. Which you can claim back once the information is provided, or at the end of the tax year. I don't know if you can legitimately decide to not provide a P45 for some personal reason, but it could be an expensive decision (in the medium term).

I would say this definitely reflects your personal stance on privacy, I think most people would rather have the money they earned sooner rather than later.