Google Ads allows advertisers in its multi-source conversions beta to supplement website tag records with backend data. According to Google's documentation, a matching transaction can supply missing customer information and permanently replace the value recorded by the tag. The value update takes effect after an initial 14-day trial.
The beta connects data from a CRM or order database to a Google Ads website conversion action through Data Manager or its API. It is limited to website actions implemented with code through the Google tag or Google Tag Manager. Imported Google Analytics conversions and URL-based conversion actions are outside the documented scope. Google also says the beta may not yet be accessible to every advertiser.
The transaction ID provides the connection between records. Uploaded data requires that identifier and the conversion's date and time, together with attribution identifiers or the specified address details. The ID must match the format and value sent by the tag. Matching and duplicate removal take place inside the conversion action to which the backend source is attached. They do not reconcile two separate conversion actions in the same account or campaign goals.
Google describes different treatment for different parts of a matched record. Missing user-provided information, such as an email address or telephone number, can be supplied by the backend upload. Its value and currency can replace the tag's values. Other fields already captured by the tag, including a click identifier, are not overwritten by the matching upload. A transaction with no corresponding tag event instead creates a new conversion, which Google then tries to attribute using the identifiers supplied.
There is a staged introduction for a newly connected source. During the initial 14 days, supplemental conversions can appear in reports and diagnostics but do not influence bidding. Value replacement is also disabled during that period. Once it ends, the added conversions automatically become eligible for bidding and the value-update restriction ends. Reporting visibility during the trial therefore differs from eligibility to affect bids.
Advertisers must supply values in the correct units. Google does not automatically convert a number expressed in cents into the equivalent number of dollars. A numeric upload can change both reported value and value-based bidding signals; zero is accepted, including for a full refund, while NULL leaves a record's value without an update. Outside the trial, replacement of the original tag value is permanent. Google also limits supplementation to consented events, falling back to account-level consent defaults when row-level information is missing.
Search Engine Roundtable covered the documentation on September 16 and noted an earlier change in the feature's name. Google has not specified a first-launch date in the help page.