What is CAC payback period?
Reviewed by CA Apurav GargLast reviewed
In short
The CAC payback period is the number of months a cohort of new customers takes to earn back, in contribution, what was spent to acquire them.
Want help applying this to your own accounts?
We handle bookkeeping, GST and TDS for D2C and marketplace sellers, and can walk you through how this works in your business.
How it is worked out
- Take a cohort: the customers whose first order was delivered in one month.
- Work out the blended CAC for that cohort: all acquisition spend divided by those customers.
- Track the cohort's cumulative contribution per customer, month by month: the first order's CM2 plus the CM2 of every repeat order to date.
- The payback period is the month in which cumulative contribution first equals or passes blended CAC.
If the first order alone earns more than CAC, payback is immediate. If contribution never reaches CAC within the period you track, the cohort has not paid back, and every new customer of that kind loses money.
Why contribution, not revenue
Payback measured on revenue looks far shorter than it is, because revenue includes the product cost, GST, marketplace or gateway fees, shipping and returns. Only the contribution left after those costs can repay acquisition spend. Use CM2 (after fulfilment, shipping, RTO and payment costs) and say which level you used.
Why it matters
- Cash. The payback period is how long each new customer ties up cash. A brand growing fast with a long payback needs funding to keep growing, even if each customer is profitable in the end.
- How much to spend. A shorter payback lets a brand recycle the same cash into acquisition more often. Many brands set a ceiling on payback and cap CAC to stay inside it.
- Comparing channels. A channel with a higher CAC can still be the better one if its customers repeat faster.
What goes wrong
- Reading a young cohort as final. A cohort acquired three months ago has no twelve-month figure yet. Compare cohorts at the same age.
- Assuming repeats happen evenly. The working above draws a straight line between two checkpoints. Real repeat orders bunch around replenishment cycles and sale events, so treat the result as an estimate.
- Ignoring returns on repeat orders. Repeat orders get returned too. Count their CM2 after returns.
Example in rupees
A cohort of 760 delivered customers cost ₹750 each to acquire (blended CAC). Their contribution (CM2) per customer builds up like this:
| Months after the first order | Cumulative CM2 per customer |
|---|---|
| 0 (first order) | ₹360 |
| 3 | ₹507 |
| 6 | ₹675 |
| 12 | ₹948 |
| 24 | ₹1,284 |
The ₹750 is reached between month 6 (₹675) and month 12 (₹948). Assuming repeat orders arrive evenly in between:
6 + (₹750 − ₹675) ÷ (₹948 − ₹675) × 6 = 6 + 75 ÷ 273 × 6 = about 7.6 months.
Until then the brand is funding these customers from its own cash. The figures are illustrative.
Related terms
Work it out for your business
Want help applying this to your own accounts?
We handle bookkeeping, GST and TDS for D2C and marketplace sellers, and can walk you through how this works in your business.
General information only, not professional advice. Rules and rates change — check the official source before you act.