How to spot and prevent affiliate fraud

Every founder who runs an affiliate program eventually asks the same question, usually right before they hit publish on their first program page. “What if someone tries to game this?”

It’s a fair question. Affiliate fraud is real, and losing money to someone you trusted enough to let into your program is the kind of experience that sours people on running programs forever. I understand the fear. I’ve seen it happen to people.

The good news is that 90% of affiliate fraud is one of three patterns, and all three are preventable with a mix of automatic protections and simple manual review. You do not need a $500/month fraud detection service. You do not need machine learning. You do not need to hire a full-time compliance person. You need to know what to look for and run a tight ship for the first month of any new affiliate relationship. That’s it.

Let’s walk through the three patterns.

The three patterns of affiliate fraud you’ll actually see

In 95% of cases, affiliate fraud at small-to-midsize programs falls into one of these three buckets. Learn what they look like and you can catch the vast majority of problems before they cost you real money.

The first pattern is self-referrals. The affiliate buys their own products using their own tracking link or coupon code so they can earn a commission on the sale. This is the most common form of affiliate fraud by a wide margin. Sometimes it’s casual (“I was going to buy this anyway, might as well earn the commission”). Sometimes it’s deliberate (“I’m going to buy 10 gift cards through my link and net 25% on each”). Either way, it’s money you shouldn’t be paying because the sale didn’t come from a genuine referral.

The second pattern is coupon stacking. An affiliate publishes their coupon code on deal sites and coupon aggregators. Customers who were already going to buy find the coupon, use it at checkout, and the affiliate earns a commission on a sale they had nothing to do with. The customer thinks they got a deal, the affiliate thinks they earned a commission, and you paid both the discount and the commission on a customer you already had. This is what “most affiliate programs suck” is really about. You’ve been intercepted by parasites.

The third pattern is fake leads. This one only applies to lead-generation programs where you pay a flat bounty per qualified lead rather than a percentage of a sale. The affiliate fills out the lead form themselves, usually with a throwaway email and a plausible-looking name, and earns the bounty. Done at scale, this pattern can turn a lead-gen program into a money pit before you realize what’s happening.

Each pattern has a different fix. Let’s go through them.

How Siren prevents self-referrals automatically

Siren has an always-on mechanism that catches the most common self-referral case. When a collaborator logs into your WordPress site and then makes a purchase, Siren detects the login, identifies the user as a collaborator, and invalidates any active opportunity tied to them. No engagement fires. No conversion is created. The self-referral attempt dies before it ever produces a commission.

The full mechanics are at self referral prevention, but the short version is that you don’t need to do anything to enable it. It’s on by default, it runs automatically, and it catches the majority of casual self-referral attempts without any operational overhead on your end.

Here’s the honest part. It has limitations. If a determined affiliate uses guest checkout (without logging in), or checks out under a different email address that isn’t linked to their Siren account, the automatic protection won’t trigger. The mechanism keys off the login event, so if there’s no login, there’s no detection. A sophisticated bad actor can work around it.

In practice, this limitation matters less than it sounds. Most self-referrals are casual, not sophisticated. The affiliate isn’t running an elaborate scheme, they’re just trying to get a commission on a purchase they were going to make anyway. The automatic protection catches almost all of those cases, and the rare determined attempts can usually be caught in manual review when you notice the pattern (same shipping address as the affiliate, purchase immediately after signup, etc.).

If you’re running a high-value program where a single bad conversion could cost you thousands, you should probably do more than rely on the automatic mechanism. But for most programs running sub-$500 transactions, the built-in protection is sufficient.

How to catch coupon stacking

Coupon stacking is harder to catch because it doesn’t always look like fraud. The affiliate isn’t doing anything technically against the rules. They’re publishing their code on a public site, and customers are finding it. Whether that’s fraud depends on whether those customers would have bought without the code, which is a question you can only answer by looking at patterns.

The signal to watch for is coupon-driven conversions that don’t come with any accompanying referral traffic. If an affiliate’s coupon code is driving 50 conversions per month but their referral link is only driving 5 clicks, that’s a red flag. Real affiliate promotion produces clicks. If you see commissions without clicks, the affiliate isn’t actually promoting your product, they’re letting the coupon do the work on sites where your existing customers are already looking.

Another signal is geography and timing. If coupon uses cluster around the hours and regions where your direct traffic peaks, that’s another sign that the coupon is being found by existing customers rather than being shared with a new audience. Cross-reference coupon conversions against your normal conversion patterns and look for suspicious overlap.

The fix for coupon stacking is usually to change how the coupon itself works, not to punish the affiliate. A few options.

Rate-limit the coupon so each customer can only use it once. This kills the repeat-coupon-site traffic because the same person can’t keep coming back for the discount.

Shorten the expiration window on the engagement (the window during which a coupon use counts toward an affiliate’s commission). A 7-day window still captures legitimate referrals without giving parasites a month to collect. The shorter the window, the less attractive it is for deal-site parasites to pursue. Cookie duration and attribution windows covers how that setting works and where to change it.

Move to a tracking-link-only structure for affiliates who are producing suspicious coupon patterns. You can tell them “hey, coupons aren’t working for you, let’s switch to tracked links only” without accusing them of anything, and it usually either solves the problem (because the affiliate was acting in good faith) or causes them to go dormant (because the affiliate was gaming you and no longer has a way to do it).

How to catch fake leads

Fake leads are the easiest pattern to catch because they leave fingerprints. Manual review of your lead conversions in the first month of any new lead-gen program will surface most of the fraud.

The fingerprints to look for. Same email domain across multiple leads (especially throwaway domains or unusual combinations). Same IP address behind multiple submissions. Form completion times that are either suspiciously fast (the submitter isn’t actually reading the form) or suspiciously identical (a script is automating the submission with consistent delays). Names that look like they came from a random generator. Phone numbers that don’t route. Companies that don’t exist when you search for them.

None of these are slam-dunk evidence on their own. But a lead that has three or four of these signals is almost certainly fake, and you can reject it without a second thought.

The review process is simple. Once a week, open your lead conversions for the past seven days, sort by affiliate, and look at anyone producing a volume of leads that stands out. Flag the suspicious ones. If you find a pattern, reject the conversions and reach out to the affiliate for an explanation. Sometimes they have a legitimate reason (they’re running a lead-capture campaign with a specific audience). Sometimes they don’t respond, in which case you know what happened.

When a collaborator pushes back on rejected conversions, the investigating a collaborator dispute walkthrough shows you how to trace the attribution pipeline back through opportunities, engagements, and conversions to figure out what actually happened. Use it as a script for the conversation. “I looked at the opportunity for this lead, and here’s what I found” is a much better position than “I just don’t believe you.”

The single most important protection

All of the above is useful, but there’s one protection that matters more than all of them combined. Don’t auto-approve conversions for new affiliates.

When a new affiliate joins your program, their conversions should land in pending status, not approved status. You review the first wave manually. You look at whether the sales make sense, whether the referral traffic matches what you’d expect, whether the pattern looks legitimate. Only after they’ve established a track record of real referrals do you switch them to auto-approval.

This one change prevents almost all the fraud scenarios described above. A self-referral attempt gets caught in pending review before the commission is paid. A fake lead gets caught in pending review. Even a coupon-stacking pattern becomes obvious in pending review because you’re looking at the conversions directly and noticing that they don’t come with click activity. Manual review is annoying for the first week of a new affiliate relationship, but it’s free, it catches everything, and once the affiliate has proven themselves you can stop doing it for that specific person.

The full concept of what a conversion is and how it moves through the pipeline is covered at what is a conversion. Understanding the states a conversion can be in (pending, approved, rejected) is the foundation of manual review, because the whole workflow depends on you holding conversions in pending long enough to actually review them.

When to escalate to a fraud service

99% of programs never need a dedicated fraud detection service. The three patterns above cover almost everything you’ll see in practice, and the protections above will catch almost everything you need to catch.

The cases where you might want more sophisticated tooling are rare and specific. If you’re running a program with transaction sizes over $1,000 each, where a single fraudulent conversion could cost you serious money, you probably want a dedicated fraud check on each conversion. If you’re in a category with known fraud problems (gift cards, gambling, high-ticket digital goods), you probably want more than basic manual review. If you’re dealing with an organized fraud ring (multiple coordinated accounts, forged identities, etc.), you’re past what any DIY approach can handle and you need specialized help.

For everyone else, the honest answer is that manual review plus Siren’s built-in protections plus the three patterns above is enough. Don’t pay for tools you don’t need.

A checklist for new program operators

Here’s the short version you can follow from day one.

Leave self-referral prevention enabled. It’s on by default. Don’t turn it off. Don’t try to “improve” it. Let it run.

Hold all conversions in pending status for the first month of any new affiliate relationship. Review every conversion manually before approving it. After 30 days of clean activity, you can switch that specific affiliate to auto-approval.

Review your coupon-driven conversions weekly. Look for coupon activity that doesn’t come with accompanying click activity. If you find it, change how the coupon is structured or move the affiliate to tracked-links-only.

Review lead conversions in any lead-gen program weekly. Look for the fingerprints of fake leads (duplicate domains, suspicious IPs, implausible data). Reject the obvious cases without apology.

Watch for the three patterns. Self-referrals, coupon stacking, fake leads. Almost every fraud case you’ll encounter fits one of them.

Don’t panic and don’t overbuild defenses. Most affiliates are honest. The ones who aren’t will almost always get caught in the first month if you’re paying attention, and the small number that slip through will show themselves in patterns that become obvious over time.

Running an affiliate program is not a fraud game. It’s a trust game. You’re building relationships with people who want to promote your product, and the vast majority of them are acting in good faith. Protect yourself from the small minority who aren’t, but don’t let the fear of that minority keep you from building the program in the first place.

Swim fast, dream big!