FFP Service Contract contains FAR 52,243-1 Alt I . Contract originally awarded competitively. Contract mod issued to extend period of performance for specific task activities within the overall contract period of performance. (not an extension of the contract period of performance.) Requires certified cost pricing data. Contractor submitted proposal 6 months ago with not to exceed amount. Due to reasons which are not clear to me, the mod / propopsal was not acted upon so six months of performance has now been incurred. Requested cost anlaysis and the analyst insists since 6 months of performance has ensued that the contractor must submit actual costs for the work already performed under the change order. Is this correct if it is a FFP contract? I see FAR 43.204 requires CO to make sure cost analysis is performed if required under FAR 15.404-1© and while the various cost anlaysis techniques refer to verifying projected costs based on historical trend and comparison of costs proposed with actual cost previously incurred, is there no difference when it's a FFP contract? Does the contractor have to provide the requested actual costs for the first six months performance of the undeifinitzed contract mod proposal?