Which FAR part governs subcontractor consent and oversight, and when do I need the CO's OK to add a sub?

The requirement for consent to subcontract is typically found in FAR Part 44, specifically in clauses like FAR 52.244-2, Subcontracts (Cost-Reimbursement and Letter Contracts). Your COR is correct that this is often a requirement on cost-reimbursement contracts, which aim to pay for allowable incurred costs and establish an estimated total cost as a ceiling. This contrasts with a time-and-materials contract, where the government pays direct labor hours at fixed hourly rates plus actual material costs, and the need for consent might be less frequent or tied to different thresholds within the specific task order. The purpose of consent is for the government to ensure that the prime contractor is performing adequate price analysis and is selecting suitable subcontractors. A consent package usually includes a copy of the proposed subcontract, the prime's cost or price analysis, and the rationale for selecting the subcontractor. The time for a contracting officer's review can vary depending on the complexity of the subcontract and the agency's internal processes; there is no set FAR-mandated timeframe. For state and local procurements, the requirements would be governed by the specific state procurement code and the relevant vendor guide for that purchasing entity.