Two kinds of click ID, and why they never swap

“Pass the click ID” sounds like one instruction. It is two, because two different systems create click IDs, and each one only means something to the system that made it.

An ad platform’s click ID identifies a click on that platform’s ad. A tracking platform’s click ID identifies a visit in that tracker’s records. Both travel in the URL. Both get stored with the lead. Both go back when the sale happens. They go back to different places, and neither one can stand in for the other.

The two kinds side by side

Read from each vendor’s own documentation on 12 October 2026. Every row is in facts above with its source.

	Who creates it	Example parameter	What it identifies	Where it goes back
Ad platform click ID	Google Ads	gclid	One click on a Google ad	Google Ads, in an offline conversion import
	Meta	fbclid	One click on a Meta ad	Meta’s Conversions API, wrapped in fbc
	Microsoft Advertising	msclkid	One click on a Microsoft ad	Microsoft’s offline conversion API
Tracking platform click ID	impact.com	im_ref	A consumer journey, which can hold several clicks	impact.com’s Conversions endpoint
	Everflow	transaction_id (the name is configurable)	The click on the partner link	Everflow, in the postback

The click ID glossary entry covers the first kind: what the ad platform’s ID is and where it breaks. This piece is about keeping the two kinds apart.

What each kind is for

The ad platform’s ID closes the loop with the ad platform. Google Ads gives a GCLID for every click, and its offline import asks for that same GCLID back. Microsoft’s offline conversion object has a field for the MSCLKID. Meta’s Conversions API takes the fbclid it put in the URL, wrapped in an fbc value. In each case the platform looks the ID up in its own click records. An ID it did not issue matches nothing.

The tracking platform’s ID closes the loop with the tracker. impact.com appends im_ref through its partner link and expects the stored value back with the conversion. Everflow expects its transaction ID back in the postback. The tracker uses its ID to find the visit, the partner and the offer. Google has never seen that ID.

The two can also mean different things. A GCLID is one click. impact.com says one of its IDs can cover several clicks in a single consumer journey. Counting the two as if they were the same unit gives two different totals for the same traffic.

One site, two IDs, two return paths

A site runs Google Ads and an impact.com partner program:

1. Visitor A clicks a Google ad. The URL arrives with ?gclid=….
2. Visitor B clicks a partner link. The URL arrives with ?im_ref=….
3. Both fill in the form. Both buy a week later.

To report A’s sale, send Google Ads the GCLID. To report B’s sale, send impact.com the stored im_ref value. Swap them and both sends fail: Google finds no click for B’s ID, and impact.com finds no journey for A’s.

The same rule holds when a tracker sits in front of your ad traffic. The tracker can follow a Google visitor under its own ID. Google Ads still matches an imported conversion only on the GCLID or on user-provided data. So the tracker has to keep the GCLID next to its own ID, and send the GCLID, not its own ID, when it reports to Google.

How the two get mixed up

1. One “click ID” field in the CRM. The form writes whichever ID came in last. A lead that arrived from a Google ad and later came back through a partner link loses its GCLID. Give each ID its own field, named after the system that issued it.
2. The tracker’s ID in the ad platform upload. The upload is accepted as a file, and every row fails to match. Upload the ad platform’s own ID.
3. “The tracker has the click, so we don’t need the GCLID.” The tracker has its click. Google matches on Google’s ID. Without it, the only fallback is user-provided data, such as a hashed email.
4. A changed value. Meta says its click ID is case sensitive. A system that lowercases URL values breaks the match without an error. Store the value exactly as it arrived.
5. UTM parameters treated as a click ID. UTMs describe the campaign. They name no single click, so no platform can match a conversion on them.

What to do

1. Store every click ID in its own field, with the system’s name: gclid, fbclid, msclkid, im_ref. One generic field is the source of most failed uploads.
2. Send each ID only to the system that issued it. Ad platform IDs go to ad platforms. Tracker IDs go to trackers.
3. Test one path per system. Click your own ad and your own partner link, convert on each, and check that the right ID arrives at the right destination.

Delivering the right ID gives the ad platform a conversion it can match to a click. It does not decide which ad gets the credit. The platform’s attribution model does that, and it is the next thing to check when the numbers still disagree.