Proration drift appears when a mid-cycle upgrade is recognized on one calendar while cash settles on another—or when a credit template fires for only one of two upgrade paths. Teams often notice it as a vague “MRR vs collections” debate. That debate is too late.
Start with a single upgraded account
Pick one customer who changed plan in the last thirty days. List every event: plan change, credit, invoice regeneration, tax line. If any step lacks an owner or a timestamp, you already have a control finding—even if the money eventually lands.
Three questions that surface drift early
First: does the credit equal the unused portion under the commercial policy you published, or under the policy engineering assumed? Second: did the new plan’s first invoice include a residual from the old plan that finance never expected? Third: did any manual adjustment bypass the template that product believes is mandatory?
Where training helps
In Subscription Billing Audit Mastery, learners rebuild these paths inside sample data until the narrative is boringly complete. Boredom is the point—surprise belongs in product launches, not in the close.