What is the ruling on participating in a compulsory savings scheme where one day's work is deducted monthly from the salary and invested, to be disbursed in full with its profit upon retirement, or to disburse a portion of it with a specified increase percentage in case of early withdrawal?

It is not permissible to subscribe to this account or fund, because benefiting from it or the profit accruing to the shareholders is usury. Its outcome is a predetermined percentage of the capital, which neither increases nor decreases. Depositing the contributions in a usurious bank or investing them therein is not permissible. However, if the total amount collected from the shareholders is invested through Sharia-compliant methods and in lawful avenues, then there is no objection to participating in it.