SaaS accounting is a specific focus for specialized CPAs because there are myriad factors brick and mortar businesses (and even ecomm businesses) don't need to consider. One of the key elements a CPA should keep in mind is the rule of 40% and measuring the trade-off between profitability and growth. If it drops below 40%, then the pricing/model should change. Moreover, SaaS by nature, needs to factor in churn which will significantly impact a CPA's projections.