Attribution is two jobs: your analytics tool's and your ad platform's

“Our attribution is wrong” can mean two different complaints. One is about a report. The other is about which ads an ad platform rewards. They are different jobs, done by different systems, with different data.

Reporting attribution answers “which channels drove our sales?” for you. Ad platform attribution answers “which of my ads drove this conversion?” for the platform. The first produces a report. The second decides what the platform optimizes toward. Fixing one does not fix the other.

The two jobs side by side

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

	Reporting attribution	Ad platform attribution
Who does it	An analytics tool, such as GA4	Each ad platform, for itself: Google Ads, Meta, Microsoft
What gets credit	Channels: paid and organic, any source the tool observed	That platform’s own ads, keywords and campaigns
Where the conversions come from	The tool’s own data collection, its tag on your site	The platform’s pixel or tag in the browser, or a server-side send from another system
Model	GA4: data-driven, paid and organic last click, or Google paid channels last click	Google Ads: data-driven (default for most actions) or last click
What it is for	Your decisions: budget across channels	The platform’s decisions: bidding, targeting, its own reports
Can it see the other platforms?	Only the visits its tag recorded	No. It sees its own clicks and views

GA4 credits a channel. Google Ads credits a click on one of its ads. The attribution model on each side is a separate setting, in a separate tool.

Sending a conversion is not attributing it

The confusion sits on the ad platform side. A conversion can reach the platform two ways:

1. From the browser. The platform’s own pixel or tag sees the conversion on your site.
2. From a server. Another system sends it: a CRM, a store, a tracking platform. Google calls this offline conversion import. Meta calls it the Conversions API. Microsoft has an offline conversion API.

In both cases the platform does the attribution. The sender delivers a conversion with an identifier: a click ID the platform issued, or hashed customer data. The platform matches it to a click it recorded and credits the ad behind that click, under its own model. Meta says server events are processed like Pixel events. Google Ads records an imported conversion with its other conversion data.

So “we send conversions server-side” describes data collection. It does not say who attributed them. The server send improves what the platform receives: conversions the browser missed, and sales that happen offline. It does not change the platform’s rule for who gets the credit.

The exception: external attribution

There is one case where your own model reaches the ad platform. Google Ads and Microsoft Advertising both accept external attribution on imported conversions:

• Google Ads: set the conversion action to Use external attribution when you create it. Each uploaded row then carries an Attributed Credit above 0 and up to 1, plus the name of the model that produced it.
• Microsoft Advertising: goals that use external attribution accept ExternalAttributionCredit and ExternalAttributionModel on each offline conversion.

Only then does the outside system’s credit split enter the platform. Without it, the platform credits its own way, whatever the sender’s report says.

One sale, attributed twice

A lead clicks a Google search ad, fills in a form, and closes as a sale in the CRM three weeks later:

1. GA4 sees the form submission through its tag. It credits a channel under the property’s reporting model.
2. Google Ads learns about the closed sale only when a system imports it, with the GCLID or the lead’s hashed email. Google Ads matches it to the click and credits the ad and the keyword, under the conversion action’s model.

Two attributions, two systems, two purposes. Neither is the “real” one. GA4’s answer goes in the channel report. Google Ads’ answer goes into its bidding.

What to do

1. Say which job you mean. “Attribution in GA4” and “attribution in Google Ads” are two settings with two models. Name the tool every time.
2. Judge a server-side setup by what it delivers. Ask how many conversions reach the platform, and with which identifier. Do not expect it to change who gets credit.
3. Use external attribution only on purpose. It replaces the platform’s rule with yours for that conversion action, and Google Ads only offers it when the action is created.
4. Do not sum the two. GA4 hands each sale to one channel. Each ad platform claims the sales it matched to its own clicks. The totals measure different things.

Both jobs run on a model, and the model names repeat from tool to tool. “Last click” is the most common one, and it does not mean the same click in GA4, Google Ads and LinkedIn.