According to China's financial system, the long-term loss of accounts received in advance should be included in income. Therefore, the unit should clean up the accounts received in advance at any time, especially those that have been aged for more than one year and have not been invoiced in time; If the contract is not implemented, the payment should be returned to the other party. If it does not need to be returned, it shall confirm the non-operating income and pay enterprise income tax.