In a Main Form called frmInv I have a text box where the control source is the calculation =[ShipQty]-[frm846820]![Tot846]. ShipQty is a field from the main form.Tot846 is a calculated textbox from the footer of subform frm846820. After each record is added to the subform Tot846 is updated which in turn updates the textbox in the main form. This works as desired. I also would like to update a QtyBal field in the table tblInv that is the data source via query to the main form. Is this possible? What would be the best approach? Thanks.