These are incomes received early, which contribute to Deferred Income. Costs already incurred or bound, corresponding to those incomes, are subtracted.
At first, it may seem that all income receipts should belong to this group. However, advance receipts, for which the company has a return obligation (for whatever reason), must be classified in Liabilities since there is a risk of return. E.g.: Rent Received in Advance: in the absence of a clause for reimbursement of amounts already paid, this account can be classified as Deferred Income.