I'm not sure if this is a stupid question, I'm Brazilian and I live in Spain, so I know the laws basically from these two countries only. I see a lot of posts here (which I assume are from the USA) where people say that the employer reduced the employee 's hours and therefore the salary without a signed contract or email or physical evidence of agreement from both sides. Is this even legal, or it depends of the State that you're living on?
From all the companies that I worked at, i always had a contract stipulating the hours per week to work and the salary, and it's against the law (in Brazil and Spain) for the employer to just reduce either one of those without a signed document from the employee. I only know one case where a colleague started working less hours and receiving less because he chose to, to be able to do a master in the university (and of course he had to sign a document with the new hours to be worked and the updated salary reduced).