- Definition
- An affiliate ID is the code in a tracking link that tells a merchant or network which partner referred a visit.
In plain words
Every partner in an affiliate program gets a code. When a visitor arrives through that partner's link, the code travels in the URL so the sale can be credited. That code is the affiliate ID.
It might look like aff_id=2231, a segment in the link's path, or a value passed through a network's redirect.
Why it matters for brand and paid search teams
The ID is the bridge between an ad seen on a search and a partner in the program. Without it, an affiliate manager sees only a domain; with it, they know which partner to talk to.
It also helps separate partners that share a domain, such as a coupon platform used by many publishers, and spot IDs that appear where they should not, such as on the brand's own search.
How it works
Programs pass the ID in different ways, but the same program usually uses the same pattern for every partner. Google documents the URL parts an ad can carry: the final URL, a tracking template and a final URL suffix, which is where partners and networks put their parameters.
An ID in a URL shows that the parameter was present when the URL was captured. IDs can be copied, reused or misconfigured, so a match does not prove who placed the ad or that a commission was paid.
Example
Northstar's program uses the parameter aff_id. Its registry maps 2231 to trailpicks.example and 4471 to bootdeals.example. On northstar coupon in Los Angeles, a saved ad's destination carries aff_id=9120, which is not in the registry.
The unknown ID stays visible in the report. The affiliate manager asks the network who holds it before deciding anything.
Fictional brands and domains, for illustration only.
Common mistakes and misconceptions
Any parameter in the URL is an affiliate ID. UTM tags, click identifiers and campaign codes are common too. Tell your tool which parameter your program uses.
An ID match proves the partner placed the ad. It is strong context. Confirm with the partner or network, since IDs can be copied.
Unknown IDs can be ignored. They may belong to sub-affiliates or new partners. Keep them visible and ask the network.
How to monitor it in Ads Lighthouse
Tell Ads Lighthouse the name of your affiliate query parameter and, optionally, a directory of IDs and partner names. It reads the value from saved Google ad destinations with an exact match, reports each ID with its observations, and keeps unknown IDs visible.
An Affiliate ID observed alert can notify you by email, Slack or webhook. Before you set a parameter, Ads Lighthouse flags common affiliate markers in destination URLs for you to review.
Frequently asked questions
Where do I find my program's affiliate parameter?
Look at a tracking link your network gives partners and find the part that changes from one partner to the next. That parameter name is what to configure.
What if my program uses redirects instead of parameters?
Ads Lighthouse traces eligible destinations from its servers, one hop at a time, and records your affiliate parameter when it appears in a later hop. A trace shows one visit from its servers, so a searcher's chain may differ.
Can I add partner names to IDs?
Yes. An optional directory maps IDs to partner names so reports and alerts show who each ID belongs to.
Official sources
Sources checked on .