1.) Does this person need a cage code to be in SAM?
2.) Does this individual need to be registered in SAM as a business? or can they be hired without registering?
3.) How would the government establish responsibility for this individual?
I could not find any regulatory or statutory requirement for a consultant to be registered in the System for Award Management (SAM). And the SAM Non-federal User Guide dated 1 Feb 2019 didn't shed much light on the topic either other than to say that registration is required for all companies wishing to be eligible for federal contracts or for federal assistance opportunities. I was, however, able to find the answer to your question in the Final Rule that was issued by DoD, GSA and NASA to update the instructions for registration in the System for Award Management (See Federal Register, Vol. 83, No. 187, Sep. 26, 2018, Part II -- Discussion and Analysis). In response to comment # 5 --APPLICABILITY TO SUBCONTRACTORS, the Councils stated unequivocally, "Subcontractors or consultants to prime contractors are not required to be registered in SAM."
With respect to your question #3 which asked "how would the Government establish responsibility for this individual", the prime contractor has privity of contract with its subcontractors including consultant subcontractors and, therefore, would have responsibility of management, oversight and payment to that individual consultant. Additionally, the prime would be responsible for flowing down the appropriate clauses to the subcontractor. According to FAR 46.405(a), "Government contract quality assurance on subcontracted supplies or services shall be performed only when required in the Government’s interest....When appropriate, the prime contractor shall be requested to arrange for timely Government access to the subcontractor facility." Therefore, the government does have the right to inspect the subcontractor consultant but only to the extent required to safeguard the Government's interest."
One last consideration is whether or not the consultant hired by the prime is truly a subcontractor as defined by the FAR: "'Subcontractor means any supplier, distributor, vendor, or firm that furnishes supplies or services to or for a prime contractor or another subcontractor." The key question here is whether or not the consultant is furnishing any portion of the supplies or servicers under the contract. If any part of the work being performed by the consultant is specified in the prime contract, then the consultant would be considered a subcontractor under that contract. However, a consultant hired by the prime to provide general advice, which does not constitute performance of any aspect of the contract work, would not be considered a subcontractor. If the consultant meets the FAR definition of a subcontractor, then the appropriate FAR/DFARS clauses (including the inspection clauses) need to be flowed down to the consultant subcontractor. However, if the consultant was hired to provide advice to the prime about their contracts (one of which happened to be the contract in question) such work would more than likely not be considered performance of the specific contract work in question, and, therefore, would not constitute a subcontract.