If you had a written contract for a specific period of time, the employer must pay you the contracted amount for that period of time. If your "signed offer" calls for at-will employment, the employer can legally reduce your pay, as long as the reasons for doing so are based on legitimate business needs, and not for discriminatory purposes. There may be other factors to consider, however, such as whether you suffered damages in reliance on the employer's false representations regarding how much you would be paid. For example, did you relocate, only to find that the job was going to pay less after you got there?
