The Rule of 40 is simple: revenue growth rate plus EBITDA margin should hit at least 40%. Most finance teams treat it as a report card. Here's why you should be running it forward, before the budget is locked, not after the quarter closes.

Expansion revenue now accounts for 40% of new ARR across SaaS. For companies above $50M, it's closer to 60%. Yet most FP&A teams model new logo acquisition down to the rep level and treat expansion as a single line called "upsell." Three metrics deserve their own models: NRR by cohort, expansion rate by product line, and time-to-first-expansion. Here's how to build them.