Tech Corner: SubIDs

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How to enhance affiliate link tracking

Written by Josh Hutter

Welcome back to FMTC’s Tech Corner, where we take a deep dive into our tools and technology. Today, we’re discussing SubIDs (aka the pass-back parameter) and how to make them work for you.

What is a SubID?

A SubID is a pass-back parameter tag generated at the end of an affiliate link for tracking purposes. It helps identify the origin of your visitors and specify unique traffic source values, allowing you to determine which links work best.

You can track any variable with a SubID, such as user attributes or link placement. Some common traits to track include:

  • Page landings
  • Sub-affiliates
  • URLs of sources
  • Link positioning on the page
  • Different websites
  • Calls-to-action
  • Keywords
  • Affiliate ID

SubID Link Structure

Here is the parameter for SubID within the FMTC platform:


You must add a “?” if no other parameter is included in front of the SubID parameter; if there is another parameter, you need to add “&” instead.

SubID parameter template

The link below is an example of a “?” link, as there are no other parameters aside from SubID. The FreshReach® link shows the SubID as an additional parameter after “c=deal-code” and therefore uses an “&”.

SubID parameter examples

The parameter is available on all shortlinks as well as FMTC’s FreshReach® links.

Network SubID Parameters

Most networks support the SubID parameter, although each network handles it differently. FMTC normalizes and standardizes the SubID to ensure that it is properly passed through all your links. Each affiliate network has unique SubID parameters. The following table will show you how they are handled with other network monetization platforms:

Table of network SubID parameters

Passing SubIDs Through FMTC

FMTC does not pass the SubID by default; it needs to be turned on through the FMTC Deal Feed Settings. This will fill out the SubID parameter with the default SubID field to all the deals that are associated with the account.


In addition, if the merchant supports deep linking, you can add a unique SubID to each new link you generate. This can be found on an individual merchant page through FMTC’s Program Directory.

FMTC Link Builder

To pass the SubID, add the parameter at the end of the affiliate link, and it will be recorded and passed through the link. To properly add a URL parameter, you must add either the “?” or “&” symbol (depending on if it is the first parameter or not in the URL) followed by the name of the parameter, which in FMTC’s case will be “sid.” You can then set that value of your choosing so you can locate and track it later.

SubIDs are an additional way to enhance the tracking of your promotional links through the URL parameters. Attributing specific link locations to revenue sources allows you to make informed business decisions.

As always, our team is ready to help you! If you have any questions or concerns, feel free to contact your account manager or email us at [email protected]. Curious about other FMTC technologies? Find more information on FMTC’s tools in Tech Corner:

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