Is it permissible for an employee to submit fictitious invoices to cover the summer and winter allowances he spent on his wedding preparations, or must he repay the amount due to his inability to provide genuine invoices? And is it permissible for him to submit fictitious invoices now, then go on a honeymoon later to justify the amount?

The aforementioned allowance is a conditional gift. As long as the company stipulates that it be spent for a specific purpose, its condition must be adhered to. If it is spent on something other than what was specified, that would be unlawful, and its value must be returned. Submitting fictitious invoices is lying, deception, and forgery, and it does not permit spending the amount later on entertainment. It is permissible to borrow without interest to repay the amount, or to seek permission from the company for a grace period for repayment, or to pay in installments, or to be forgiven.