Margin account is a restricted bank deposit, but the ownership still belongs to your company, but its use is limited and it has certain guarantee function. The bank also gave it interest according to special deposits. This interest belongs to your company and can be borrowed from other monetary funds-deposit, loan: financial expenses-interest income.
If it has expired for many days and there is still 300,000 yuan in the deposit account, I suggest you contact the bank to confirm whether 300,000 yuan has been withdrawn from the company's current account. If so, the deposit and interest can be transferred back to the company's basic deposit account.