What is the ruling on falsifying a fictitious marriage contract to increase one's salary, and how can one absolve themselves of this act after repentance and remorse, given the lack of financial means?

Public Muslim funds are inviolable, just like their private funds, and the ruler organizes the affairs of the public treasury (Bayt al-Mal). If the public treasury is well-ordered, it is not permissible to take anything from it without the ruler's permission. However, if the public treasury becomes corrupted, jurists have differed on the permissibility for a Muslim to take what he is entitled to without the ruler's consent. Based on this, if the increase you took was commensurate with your essential needs, then there is no blame upon you, provided you do not repeat it. But if the increase was more than your need, then you have no right to it, and it must be spent for the benefit of the Muslims. Regarding the sham contract, if it was a forgery without offer and acceptance, the matter is clear. However, if it involved offer and acceptance, it is a valid contract, and the absence of intention to marry does not affect it, according to the Prophet, peace and blessings be upon him, who said: "There are three matters, serious in earnest and serious in jest: marriage, divorce, and revocation [of divorce]."