Debit: 500 in the bank.
Credit: Special Payable 500
When in use
Debit: special payable
Loans: bank deposits
As for how long you can hold an account, it depends on the implementation of the local tax authorities. Generally, there should be no problem within 2-3 years. After that, the tax will transfer you to "non-operating income" to pay income tax.
If you do "deferred revenue", it is the same, and it will be included in "non-operating income" by stages. How long will it take? You still have to communicate with the tax authorities.
Suggestion: If the cash flow of the enterprise is ok, it should be included in the "non-operating income" at one time to calculate the tax, and the expenses can be directly charged in the future.
I hope I can help you!