So true, Mark. To make this solid post even more applicable to enterprise B2B companies (it feels a bit B2C focused to me), you may want to add the concept of CRC (Customer Retention Cost) on top of the CAC when calculating the cost to obtain the TLV. In this framework, CAC is the sales+marketing costs to land the initial deal. CRC is the cost to on-board/implement and manage the customer over the “payback period” you choose (3–5–7 years, etc.). Without this cost, the customer is not likely to renew their contract, let alone expand it. Since the drivers of the CRC are very different than those of CAC it makes sense to split them up and not simply amend CAC with additional drivers. This helps ensure accountability among both the sales and marketing team and the Customer Success one.

@kaiserMF from @totango published a good framework for that metric here: https://www.linkedin.com/pulse/customer-retention-cost-new-metric-boardroom-kaiser-mulla-feroze