Essentially, the idea of contract certainty is that each party will know exactly what the reinsurance product is that is being sold at the time it is being sold, so it can be priced correctly and so the purchaser knows exactly what it is buying without any later misunderstandings. The 9-month rule, which comes out of Part 23 of SSAP 62, requires that the reinsurance contract be finalized—reduced to written form and signed within 9 months after commencement of the policy period—but allows the contract to incept before the contract is finalized.