A SubID is a custom parameter added to an affiliate tracking link that lets the partner label the origin of each click at whatever level of detail they need — the traffic source, the specific placement or zone, the campaign, the creative variant, the A/B split, or a sub-partner.
Definition
A SubID is a custom parameter added to an affiliate tracking link that lets the partner label the origin of each click at whatever level of detail they need — the traffic source, the specific placement or zone, the campaign, the creative variant, the A/B split, or a sub-partner. When a conversion is reported back, it carries the SubID values that were on the originating click, so the affiliate's tracker can break down registrations, deposits and revenue by every dimension that was tagged.
SubIDs are the backbone of optimisation. Without them, an affiliate sees only aggregate performance — total clicks, total deposits, a blended cost per result — and has no way to tell which zone, creative or campaign produced the value and which produced only spend.
With them, the same data resolves into a ranked list: these three zones drove 80% of deposits, this creative carries the campaign, that sub-partner sends traffic that converts but never retains.
In context
Trackers expose several SubID slots — commonly sub1 through sub5, or named parameters — which are passed through the click, stored, and matched on the postback. A disciplined naming scheme is essential: if sub2 means "zone" in one campaign and "creative" in another, historical analysis becomes unreliable, so buyers fix the meaning of each slot across all campaigns and document it.
Some setups also pass a pass-through SubID from the traffic source into the tracker and on to the advertiser, so the same identifier can be reconciled at three points.
The main uses are cutting losers and scaling winners. A push campaign broken down by zone SubID reveals which zones to blacklist and which to whitelist.
A social campaign broken down by creative SubID shows which angle to produce more of. A network relationship broken down by sub-partner SubID shows which downstream partners send quality and which send fraud.
SubID hygiene — consistent slots, correct macros, verified end to end before spending — is one of the highest-leverage habits in affiliate operations because everything downstream depends on it.
Worked example
A buyer splits a push campaign by zone SubID after $600 of spend. Three of ninety zones account for 80% of deposits at a $40 cost per FTD; the rest average $190. The buyer whitelists the three, blacklists forty dead zones, and cost per FTD for the campaign falls from $95 to $48.
Frequently asked questions
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