Your Lettor of Offer & Acceptance (LOA) and the C-type contract have PoPs that expire on 31 Dec, so you will be required to pay all of the allowable costs incurred and the negoatiated fee for those services/parts received up to that time.

It's further assumed that if you have a CPFF type contract for repairs, then you must also have the appropriate clauses (in the 52.245 series) in each contract covering Government Furnished Property - as the items being repaired by the contractor would need to be accounted for while in their custody. Custody of the items in repair would then be transferred from the C-type contract to the IDIQ to adequately account for the items being repaired. It's further assumed that you would have a new LOA to cover the work to be done under the IDIQ as your current LOA expires in less than 6 months.