Some assumptions have been made to provide an answer to your inquiry:

1. This is a cost type contract.
2. Consent to sub-contract was given by the contracting officer to the prime.
3. The subcontractors selected were not on the excluded parties list.
4. The subcontractor was not owned by the prime.
5. These are not commercial items purchased from the subcontractor.
6. You are not able to determine the cost/price fairness or reasonableness of the items.

FAR 15.404-1 tells us to use any of the proposal analysis technics necessary to reach a conclusion that the price of what we’re purchasing is fair & reasonable.

In this instance, the contract being evaluated is between the government and the prime. The prime is generally free to make a contract with another contractor (their sub) to supply items for their contract action. The government has the right to require the prime to substantiate that the items procured from the sub were at a fair and reasonable cost/price.

However, unless there is a clause included in the contract with the prime that specifically states that the government has the right to manage the prime’s subcontracting and make the final determination as to the suitability and selection of a subcontractor to supply those line items – the how and whom of their (prime’s) acquisitions are not subject to evaluation by the government. The government does have the authority to not accept the line items if they fail to meet the requirements spelled out in the SOW/PWS or if the prime cannot justify that the prices they paid for the line items were fair and reasonable.