He could show them W2's from the current employer.

Has anyone (OK, any SW dev in the US) ever done this? I've been in the industry for almost 30 years and no prospective employer has ever asked me what my salary was.

Not in the US, but in the UK all my jobs have asked previous salary. What's more ridiculous was one position where the recruiter was trying to convince me to take a job with a company at a lower salary than I wanted. His argument was your last salary was X so the new company aren't going to pay you y, because y was too much higher than X...

They've always asked me. But they've never asked for a W-2 to prove it.

I’ve had a few recruiters ask me. I don’t tell them anymore.

Yes, I've done this once. I was moving from the SW industry to another industry that doesn't pay nearly as well. I was asking for less than 1/5th of my salary, and they thought the number was too high. I offered my current salary to prove "we're both experiencing quite a bit of pain here..."

I think the poster was probably asking why anyone would tell a future employer this information.

Employers should pay what they value the position at, not what someone else was paying for it.

Would you refuse an employer that wanted a past W2 as a non-negotiable?

I feel like there’s a bit of trust involved in the whole hiring process. If they think I’m lying and can’t pay me what I want, then why do they believe anything I said during the interviews. I don’t want to work with people that think lying to them after a few conversations.

Yes.

But why would he? It's none of their business

I know nothing about it in the US, but in the UK it would be their business once he started and they set him up on payroll. You could still argue none of their business, 'can only harm you' in negotiating salary of course - and in a large enough org the same people would never know, but otherwise could be a short-lived deception and maybe you'd feel weird about that once colleagues.

In the US, it's asked but I learned a while ago to dodge the question if they ask. If they're genuinely unsure, that tends to be a red flag. If they have a number in mind, we just negotiate and see if we can't come to a common understanding. I say that with the understanding that negotiating isn't something that comes easy for a lot of folks. I personally have found it an extremely useful skill over the years.

Different markets will bear different negotiation tactics. California, for example, made it illegal for a potential employer to ask a candidate this information.

I meant that, negotiation aside, here it literally is their business (via form P45) in setting you up on payroll. (Unless you time it or take a break such that the new job is your only one since 6 April, i.e. in the current tax year.)

Thinking about it - I do know/can infer a little about the US - everyone does (or has someone do) their own taxes there, so it's not needed. The purpose of this in the UK is that the second employer within a tax year can set up the new employee correctly so tax isn't underpaid as a result of ignoring the previous income.

(PAYE - Pay As You Earn - income tax, national insurance contributions, and student loan repayments are handled by employer. People only 'do taxes' (self-assessment) here if self-employed, have capital gains over the allowance or sale price over the reportable amount, etc. extra curricular stuff like that that, especially because of allowances before the tax kicks in, most people don't need to. I would guess the most common reason is pension contributions made with post-tax money (employer's pension scheme is of course paid into primarily through payroll, not that) for those earning enough to have a higher marginal rate of income tax - you get the basic rate back on contributions automatically, since everyone pays it, but any extra requires self- assessment.)

It is never an employers business to know previous salaries. It's wildly I appropriate they would have stones to actually inquire