Prime Contract

Why does the CO want to see it?

ETA - past example: One of our CO's wanted to see that we had a subcontract in place prior to issuing a Task Order under an existing contract vehicle. I'm not sure if he could "require" us to show it, but we wanted the business so it wasn't an issue.

Can the contracting officer see a copy of a subcontract with the prime contract?

A CO has no inherent right to see a subcontract. A subcontract is a private business transaction. Any right to see a subcontract is a matter of contract terms. Some contract clauses would give the government access. Examples of such clauses include: 52.215-2, Audit and Records--Negotiation (MAR 2009) and 52.244-2, Subcontracts (JUN 2007). Even with those clauses, access is not unlimited.