When I was hired by Merrill Lynch, in Dublin, they asked for my bank statements for the last ten years in order to verify that I was indeed making what I said. (The only annoying thing was that I had to scan 75 pages... boooring.)

>Background checks are normally done via a 3rd party background check company, and they don't have access to this kind of data.

Yes they do. There's a company owned by Equifax called The Work Number that collects such information.

https://en.wikipedia.org/wiki/The_Work_Number

Exactly, thanks for clarifying this for me.

In the US, this is a legal minefield and when a potential employer calls a past employer for references, that past employer will very often not reveal anything more than "We can confirm that this person was employed by us from date1 to date2" and that's it.

They will not disclose your salary, what you did, your organization, who you reported to and who reported to you, your performance reviews and anything else of that nature because all of this extra information is grounds for you to sue them later if you don't get the job you're currently applying to.