Accrued income is treated in the balance sheet as an asset because accrued income is one which company has earned but the company has not received the cash for it and that is the reason why it shown on the asset side of the balance sheet.
Accrued expenses are shown on the liability side of the balance sheet because they are those expenses from which the company has received the services but the payment has not been made. Example of accrued expense would be wages outstanding .