Is the money obtained from a fictitious lease contract, where the landlord received the amount from the workplace and then handed it over to the employee without the apartment actually being rented, permissible or forbidden? And how can one dispose of it if there is a doubt about its permissibility?

The employee and the employing entity must abide by the employment contract concluded between them, unless it contradicts a Shariah ruling.

If the contract stipulates that the employee is only entitled to housing provided for their residence, and not a housing allowance, then they must return the amount to the employer. What they did is considered a betrayal that necessitates repentance and the return of the money.

If the contract stipulates their right to both, then they are entitled to the allowance if they do not find housing or choose to forego it.

If the housing allowance is not specified in the contract, this constitutes an ambiguity (جهالة) in the wage: - If the ambiguity is excessive and leads to dispute, the contract is فاسد (voidable/defective), and the employee is entitled to the wage customary for similar work (أجرة المثل), including a housing allowance. - If the ambiguity is minor and does not lead to dispute, the contract is valid.