This could be something akin to breach of fiduciary duty or self-dealing [1]. And if you have any record of the agreement that you're to have the same salary, t

This could be something akin to breach of fiduciary duty or self-dealing [1]. And if you have any record of the agreement that you're to have the same salary, that could potentially carry some legal weight. Note that I have no experience in law - you should get advice from a professional. I'm sure an hour's chat to see if there's a chance at legal restitution, before going all in, would not be too expensive. But you probably only want to use the law as a bargaining chip to get him to voluntarily reduce his salary - co-founders locked in a legal battle with each-other are sure to sink the startup. [1] https://en.wikipedia.org/wiki/Self-dealing https://en.wikipedia.org/wiki/Self-dealing