Is it permissible to pay 2.5% on the total profit and capital in commercial investments, after I used to pay 10% of the profit considering it as Zakat on crops and fruits? And what is the ruling on what I paid previously?

The zakat (definition) on invested money is a quarter of a tenth (2.5%). If the money is invested in trade goods, then both the profits and the principal are subject to zakat after a full year has passed. However, if it is invested in fixed assets not intended for sale, then zakat is due only on the returns, provided they reach the nisab (definition) and a full year has passed over them. Any amount given out as zakat before knowing the exact due amount is considered part of it. Ignorance of the exact obligation does not affect the validity of the zakat. If the amount given exceeds the due amount, the surplus is considered charity. If it falls short, the remaining amount must be paid.