When your average deal takes six months to close, the CAC number on your board deck is describing a cohort that no longer resembles the business you are running today.
Blended CAC lies by construction
Dividing this quarter's spend by this quarter's closed-won deals mixes two unrelated cohorts. The deals closing now were sourced two quarters ago, at different spend levels, through different channels.
Cohort the spend, not the revenue
Anchor every deal to the period in which it was sourced and carry the acquisition spend forward with it. The number becomes less flattering and considerably more actionable: you can finally see which channel is compounding and which is merely expensive.
- Anchor on first touch, then hold the cohort for the full sales cycle.
- Report a trailing-six-month CAC alongside the quarterly figure.
- Segment by deal size before you segment by channel — mix shift explains most anomalies.
Attribution under long cycles
Multi-touch attribution degrades as cycles lengthen, because the touches that matter most are often unattributable — a conference conversation, a colleague's recommendation, a docs page read eight months ago. Model the gap explicitly rather than pretending the tracked touches are the whole picture.
