Attribution parameters as event properties - now on by default in the Browser SDK + GTM
The Browser SDK now captures marketing attribution (UTMs, click IDs, referrer) as event properties by default, alongside the user properties it always set. The GTM template was updated with the same behavior so GTM-based implementations get it automatically, no custom variables needed.
What it is
Description: The Browser SDK now captures marketing attribution (UTMs, click IDs, referrer) as event properties by default, alongside the user properties it always set. The GTM template was updated with the same behavior - so GTM-based implementations get it automatically, no custom variables needed. This is fully additive: user property attribution continues working exactly as before, no new events are generated, and existing setups are untouched. Updating the SDK / template is the whole migration.
Why: User-property attribution is locked to a single model: most recent value, no expiration. Event properties remove that lock.
With attribution carried on the events themselves, you can leverage persisted properties to apply different allocation models (first, last, first/last known), set expirations like session scope (creating Session scoped properties), and change those settings anytime - retroactively, at query time, no re-instrumentation.
Where: Browser SDK version and the GTM template (released today).
EUDC: Yes - client-side, works with any server zone.
When: SDK is live; GTM new template live with event property attribution properties capturing on by default.
Docs: https://amplitude.com/docs/sdks/analytics/browser/browser-sdk-2#event-property-tracking