Looking at the H1B dataset it includes two fields "proposed wage rate" (what the company proposes to pay the candidate) and a "prevailing wage rate" (the market

Looking at the H1B dataset it includes two fields "proposed wage rate" (what the company proposes to pay the candidate) and a "prevailing wage rate" (the market rate). I believe companies are also required to disclose to this information to other employees on request (to provide a check that H1Bs aren't being used to replace employees with lower salary staff)