Attribution is the rule that decides who gets credit for a sale when a customer touched several ads or links on the way. In affiliate marketing the answer is usually simple and strict: the last affiliate click wins, and only that affiliate gets paid. Ad platforms and analytics tools often use smarter models, which is why their numbers rarely match the network’s.
Attribution is the method of assigning credit for a conversion to the marketing touchpoints that preceded it. A model defines the rule. Last click gives all credit to the final click before conversion; first click to the first; linear, time decay and position-based split it by fixed rules; data-driven attribution uses the account’s own conversion paths and machine learning to estimate each touchpoint’s contribution. Every model also has an attribution window, the period after a click (or view) during which a conversion can still be credited to it.
Affiliate programs almost universally pay on last click within a cookie or attribution window: the affiliate whose tracked link was clicked last before the purchase gets the commission, and no one else is paid. Amazon Associates, for instance, credits qualifying purchases within 24 hours of the click for most items. Networks enforce this with deduplication across affiliates and, for advertisers who also buy media, against their other channels, which is why a conversion visible in an affiliate’s tracker can be credited elsewhere and not paid.
Ad platforms moved the other way. In 2023 Google retired the first-click, linear, time-decay and position-based models from Google Ads and Google Analytics 4, leaving data-driven attribution as the default and last click as the alternative; Google noted that fewer than 3% of Google Ads web conversions had been using the retired models. Meta reports conversions within its own click and view windows. The result is structural disagreement: the ad platform, the analytics tool, the tracker and the network can all count the same conversion differently, and each is internally consistent.
For an affiliate the practical stance is to know which system pays (the network, on its rules), to configure the tracker to mirror those rules as closely as possible, and to treat platform-reported conversions as optimisation signals rather than revenue. When the gap between the tracker and the network grows, attribution windows, deduplication and click-ID loss are the first places to look.
In April 2023 Google announced that the first-click, linear, time-decay and position-based attribution models would be removed from Google Ads and Google Analytics 4, with the change completed later that year after a postponement to mid-July. Data-driven attribution became the default; last click stayed available. Google justified the move by low usage, saying fewer than 3% of web conversions in Google Ads used the four retired models, and by the argument that fixed rules cannot keep up with real customer journeys.
For buyers running affiliate offers on Google Ads, the change widened a gap that already existed. The network pays the affiliate on last click within its window; Google Ads now credits conversions across touchpoints according to its own model, and automated bidding learns from those credited conversions. A campaign can therefore look stronger in Google Ads than in the network’s payout report, or the reverse, without anything being broken. The fix is not to make the numbers identical but to send Google the conversions the network actually pays (approved, deduplicated) as offline or postback-based conversion imports, so the bidding learns from revenue that exists.
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The rule that decides which affiliate gets credit, and payment, for a conversion. Most programs pay the last affiliate click within the attribution window.
Last click gives all credit to the final click before conversion; data-driven attribution spreads credit across touchpoints based on observed conversion paths. Google Ads and GA4 default to data-driven since 2023.
The time after a click (or impression) during which a conversion can still be credited to it, for example 24 hours, 7 days or 30 days. It is set by the program or platform.
Usually because of different attribution windows, deduplication against other affiliates or channels, pending versus approved status, or click IDs lost in the funnel.
References are listed as plain text on purpose; look them up by title and publisher. Updated: 2026-10-06.
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