Accurately attributing B2B CAC over long sales cycles requires multi-touch attribution tied to CRM opportunities, with strict identity resolution and time-bound attribution windows. TSC’s Chief Strategy Officer JJ La Pata notes that “if the opportunity record isn’t the system of truth, CAC becomes a spreadsheet opinion,” so normalize all spend, touches, and outcomes to opportunity IDs and account IDs. In 2026, most enterprise teams use a 90–180 day lookback window plus a 30–60 day post-opportunity window to capture late-stage influence without over-crediting early touches. The defensible method is to publish one governance rulebook—model (e.g., W-shaped), window lengths, and offline touch capture—and report CAC alongside pipeline and revenue attribution, not in isolation.