CPA (cost per action, also called cost per acquisition) is a pricing model in which the advertiser pays the affiliate a fixed amount each time a referred user completes a defined action, such as a purchase, registration, app install, or first deposit. The affiliate is paid per result, not per click or impression, so the advertiser knows its cost per conversion in advance.
How it works
The program defines the qualifying action, any conditions attached to it (minimum order value, allowed countries, or a minimum first deposit), and the payout. Conversions are tracked by postback or pixel, reviewed, and then approved or rejected. Approved actions are paid at the agreed rate; reversed or fraudulent ones are not.
On the advertiser side, CPA is also a performance metric:
CPA = total cost / number of conversions
Example
Example: a fintech app pays $60 per verified account.
Clicks sent by affiliate: 2,000
Verified accounts: 80
Affiliate earnings: 80 x $60 = $4,800
Earnings per click (EPC): $4,800 / 2,000 = $2.40
The brand pays $60 per verified account from this channel, regardless of what the affiliate spent to acquire the traffic.
Why it matters
For brands, CPA limits risk: you pay only for outcomes you defined, which makes budgeting simple. The downside is that a flat CPA pays the same for a low-value and a high-value customer, so programs add qualification rules or move top partners to RevShare or a hybrid deal. For affiliates, CPA means faster, more predictable cash flow, but no share of the customer's long-term value. See CPA vs RevShare vs Hybrid for a side-by-side comparison.
Related: CPL, CPS, RevShare, hybrid deal.