Enabling Budget for Liability Account

Dear Team,

Can any one tell us do the Budgeting work for Liability Account

Requirement: Rather than using Use PO Encumbarance check box we have developed OAF page for budgeting where the controlling of budget takes place in payables.

Going indepth as we know whenever we create a invoice from Receipt(Procure to Pay) process the system defaults the accrual account from Inventory AP Account which is a Liability Account nature(account type) from the Organization setup. In this case came to know that there is no budgeting allocation for Liability account, In this case can any one help us in providing the solution how this can be acheived.