Adding retainage on a Purchase Order that represents the contract
Generally, contracts are set up in Contract Management and flows through to vendor agreements. in this scenario the purchase order represents the contract. Therefore purchase orders with retainage does not allow vendor agreements with retainage to be attached to them.
You can attach a vendor agreement with retainage to a purchase order header of a purchase order line, as long as retainage is not yet defined on the purchase order. Use Purchase Order Header Retainage (PO55.3) to add retainage percents to a purchase order header or Purchase Order Line Retainage (PO55.4) to add retainage percents to a purchase order line.