The short answer
A subscription business can report very different returns depending on whether it counts the first payment, cumulative payments, or a contract’s stated value. Pick the revenue basis before dividing by advertising spend, and label each view separately.
Use a bounded revenue horizon
For a first-payment view, count the initial payments associated with acquired subscribers. For a cumulative view, specify how long the cohort has been observed. A signed commitment, an invoice, and cash received are different events; do not combine them without explaining the report’s purpose.
Calculate realized payments
Illustrative inputs: $3,000 acquisition spend brings 50 subscribers paying $40 initially. First-payment revenue is 50 × $40 = $2,000, and first-payment ROAS is $2,000 ÷ $3,000 ≈ 0.67×. If 40 of those subscribers make another $40 payment in the next period, cumulative payments are $2,000 + 40 × $40 = $3,600. The cumulative ratio is $3,600 ÷ $3,000 = 1.2×.
Revenue payback is not contribution payback
Assume, for the example, that service and payment costs consume 25% of collected revenue. Contribution through the second payment period is $3,600 × (1 − 0.25) = $2,700. After the $3,000 acquisition spend, $300 remains unrecovered. The cumulative revenue ratio exceeds one while contribution has not yet covered acquisition.
Do not project perpetual payments
Future retention, upgrades, refunds, and servicing costs are uncertain. A model based on historical cohorts should identify the observation horizon and separate measured payments from projected amounts. Recently acquired subscribers cannot supply evidence about their own long-term retention yet.
Match the report to the decision
Use the first-payment view for immediate cash requirements and a mature cohort view for longer acquisition economics. Track cancellations, failed collections, discounts, and additional retention marketing costs. Compare cohorts at the same age and cost basis. A platform value sent at signup may be a model or fixed assignment rather than collected revenue; verify that distinction before calling its reported return realized subscription ROAS.
Follow payments into contribution
- Gather: Track first payments, later collected payments, cancellations and service costs by cohort.
- Produce: Show realized revenue return and contribution payback as separate results.
Decision boundary: Contract value and projected renewals must not be relabeled as collected revenue.
Next reading
Examples are illustrative, not client results or benchmarks. The calculations use the inputs shown; real-world decisions depend on your records and assumptions. Report a correction.