What background check do most employers use

Employment History Background Check - Will Employers Do This Without My Knowledge?

It is incredibly unlikely that an employer would do a background check without your approval. There are too many potential data breaches.

On the other hand, it is quite likely that you gave this approval when you submitted an application. Virtually every application contains a section in which you authorize the employer to take a background check. If you fail to read the disclaimers before signing / filing an application, it is very possible that you are authorizing the employer to do a background check without realizing it.

When the time comes to verify your employment, the background verification company generally calls the employer you listed and essentially asks, "Was user 87704 between Begin- and End date as Title employed ? ". If you listed an employer who was not your registered employer (i.e. the company whose logo was on your paychecks and that was listed on your tax filing), the HR person answering the call leaves when the background checking firm leaves calling just to say they have no record of ever being there, you will have no idea who a contractor has sent to their building to work.

If you've listed the wrong company, especially after you've done it multiple times, and a background check comes back stating multiple employers have no record of you, this is likely something that would make an employer just ditch you, instead trying to get an explanation there. I would generally expect an employer to ask for an explanation if the background check comes back with slightly different dates than what you provided or a slightly different title. Having multiple employers with no record of you would be a much bigger hurdle. Sure, it is possible for the employer to ask you for an explanation, but it is also possible that they decide that the likelihood that you had a large part of your experience is too high for their level of comfort.