You open your affiliate report. One partner is sitting at a gorgeous ROAS, and your first instinct is to send them more budget.
Do this math with me before you do.
Two partners, same revenue
Say both drive 10,000 dollars in sales this month.
Partner A, an influencer running content:
10,000 in sales, 1,500 paid in commission. ROAS of 6.67.
Partner B, a coupon site:
10,000 in sales, 200 paid in commission. ROAS of 50.
On paper, Partner B looks like a dream. Low cost, huge return. Easy call, right?
Here's the catch.
The costs your ROAS is hiding
First, attribution overlap. The moment you put a code out into the world, coupon sites find it, index it, and start claiming last click on it. But that sale usually overlaps with three other channels that already did the work: your paid search, your email, your retargeting. The affiliate report shows one clean conversion. Reality is a customer four channels deep who was always going to buy.
Second, the discount itself. That code isn't free. A 10 percent off coupon on 10,000 dollars in sales is 1,000 dollars out of your margin. It belongs in your cost of acquisition, but almost nobody puts it there. Add it in and Partner B's real economics look very different.
So the "50x ROAS" partner might be claiming demand you already owned, at a discount you're quietly eating.
And the low commission is doing a lot of the work
Look again at why Partner B's ROAS looked so good: they're on a low commission. That is the whole lever. A partner will only ever show you an amazing ROAS when you pay them a low rate.
Here is the uncomfortable part. Most programs keep every partner on the same commission level. So in a lot of real setups, your coupon sites are earning the exact same rate as your best content partners, on demand they didn't create. Tier your commissions by partner type, and the flattering numbers on the low-value partners drop back to reality fast.
This is why channel ROAS on its own tells you nothing
You cannot judge a partner on their isolated ROAS. What matters is blended ROAS across your whole mix, because affiliate coupon sales overlap so heavily with everything else. Two programs with identical headline numbers can be completely different underneath: one is 80 percent coupon redemptions of existing demand, the other is almost all incremental.
The number on the dashboard is only as honest as the math behind it.
How do you actually measure incrementality
You don't need a data science team. Two signals get you most of the way:
New vs returning. Pull the share of a partner's conversions that are first-time customers. Coupon and extension partners skew heavily toward returning buyers who were already at checkout. A low new-customer share is a low-incrementality flag.
Time from click to sale. Coupon clicks tend to land seconds before purchase (someone clicked the code, then bought). A longer window between click and conversion often points to a partner who actually created the demand, like content and influencers do.
So what do we actually do about it
We don't take codes away from coupon websites. Policing a code out in the wild is a losing game, and it rarely works cleanly. Most of the time, if a coupon partner isn't adding incremental value, we just end the collaboration. Simpler, and it protects the margin better.
Your action list
Check incrementality before you trust the ROAS: new vs returning share, time from click to sale.
Add the discount cost into your CPA, every time
Judge partners on blended ROAS across the mix, not their channel in isolation
Tier commission by partner type instead of running one flat rate for everyone
Break revenue down by publisher type before you judge any program
If a coupon partner isn't driving incremental value, end the collaboration instead of trying to police the code
Reward the partners bringing new demand, not the ones standing at the finish line.
Talk soon,
Jani
P.S. Want to know how much of your affiliate revenue is actually incremental? Reply to this email and I'll take a look at your program.
Missed a past edition? Read the full Affiliate Snacks archive here: https://affiliate-snacks.beehiiv.com/archive