The ostensible subcontractor rule says that, for a small business or socioeconomic set-aside such as 8(a), the small business prime contractor must perform the primary and vital parts of the contract and can’t be unduly reliant on a subcontractor. If the small business is found to violate the rule, the size of the small prime contractor and the large subcontractor are grouped for size purposes, which can result in loss of award. But the ostensible subcontractor rule is different from SBA’s joint venture rules, because SBA rules (and other federal law) distinguish between a prime-sub team and a joint venture. In a recent decision, OHA reversed a determination that a small business prime was affiliated with a subcontractor where the Area Office mixed up the analysis of the ostensible subcontractor rule and the joint venture rules.