Unless a clause prescription specifically mentions that the new requirement(s) of the clause must be incorporated into existing contracts via modification, the legacy version of the clause remains valid for current contracts. Modifying contracts each time a clause is updated would create an administrative burden for the Government and also incur additional contract costs. Contractors would require some form of consideration or an equitable adjustment in order to comply with the burden of the new requirements. That said, if a new version of a clause actually removes or reduces a burden on the contractor, the contracting officer could modify the contract to replace to legacy (and more cumbersome) version with the updated version.