The agreed upon credits would be any amount of money you and the customer agreed would not be charged by you. For example, if you had a $5,000 contract to install siding on a home using an expensive brand of siding, but then it was agreed after the fact to use a less expensive brand, then the agreed upon credit would be the difference in price between the expensive siding and the less expensive siding. Or if you had a contract to perform 10 different repairs but only performed 8, then the credit (i.e. amount of money due back to the customer or coming off the total contract price) would be equal to the cost of those 2 repair items that are no longer being performed by you.