FAQs about Google Ads conversions with multiple sources (beta)

If the option is not visible, it is because your conversion action type is currently unsupported.

Connecting an additional data source is currently only available for Google Ads website conversion actions that are set up manually using code via the Google tag or Google Tag Manager.

This requirement exists because the system is designed to supplement online tag data with offline uploads, and it relies on a unique Transaction ID to accurately match and deduplicate these events. By serving as a unique identifier for each conversion, the Transaction ID prevents the system from counting the same conversion multiple times. To ensure accurate reporting, your system must be able to reliably generate, capture, and send a consistent Transaction ID across both data sources.

The following conversion types are unsupported, and the connection option will not be visible for them:

• Non-website conversions: This feature requires a "tag + offline" data combination. Because non-website conversions do not use a website tag, they cannot be used.
• URL-based (codeless) conversion actions: These setups cannot dynamically capture the required Transaction ID from the website to send to Google Ads.
• Imported Google Analytics conversions: This feature is currently designed specifically for Google Ads web tags. If you track conversions using Google Analytics, the data merging and deduplication process must happen within Google Analytics itself before the data is imported into Google Ads.

No. To ensure your campaigns remain stable while you verify your setup, your additional data source will automatically enter an initial 14-day trial period. During this time, your existing tag-source conversions will continue to be biddable as usual. Data from your new offline source will be used for reporting and diagnostics only, allowing you to safely resolve any setup issues. After 14 days, the conversions from the additional source will automatically become biddable.

Learn more about fixing diagnostic alerts for conversions with multiple data sources

We don't recommend testing with a duplicate conversion action. Creating a duplicate requires additional manual work to update your website tags and recreate the exact conversion action settings, and even minor setup discrepancies can lead to unreliable comparisons.

If you must proceed with a side-by-side comparison, expect a temporary reporting gap where the new action shows fewer conversions while Google's conversion modeling calibrates. For the most accurate results, you should allow a 28-day warm-up period, use the "All conv. (by conv. time)" metric, and expect minor variations.

Google Ads prevents double-counting by matching the Transaction IDs from both data sources within the same conversion action.

When your offline upload and your website tag send the exact same Transaction ID, our system recognizes it as a single event. Instead of counting it twice, Google Ads will deduplicate the event. If your offline upload contains a new conversion value for that matched ID, Google Ads will use it to update the existing conversion rather than counting a new one.

After connecting an additional data source, we recommend monitoring your setup to ensure your transactions are deduplicating correctly:

• Conversion Diagnostics: Navigate to Goals > Conversions > Summary and click the Diagnostics tab.
• Review Alerts: This tab flags specific issues that prevent deduplication, such as:
  • "Your conversions may be overcounted": This indicates a low match rate between the transaction IDs in your tag and your additional data source.
  • "Google tag is missing transaction ID": This warns you that your tag is failing to send the required IDs for matching.

While you can upload a database containing historical purchase data, uploading a year's worth of data won't improve your current campaign performance. Google's Smart Bidding algorithms rely on fresh, recent data to make real-time optimization decisions.

Here is how Google processes older historical data:

• Impact on bidding: While the system accepts older data for reporting purposes, it won't give you a performance boost. Late uploads are deprioritized by Smart Bidding models and may be ineligible for features like enhanced conversions matching.
• Value adjustments: If your upload includes updated conversion values for transactions already recorded by your tag, these updates will only be processed for conversions that occurred up to 55 days in the past.

Best practice: Your ongoing data strategy should prioritize freshness over historical backlogs. We strongly recommend syncing your internal systems with Data Manager so that your data is uploaded within 24 hours of the conversion event occurring. This ensures your data is eligible for both enhanced conversions matching and optimal Smart Bidding optimization

Currently, the Google Ads Data Manager UI allows you to connect only one additional offline data source to a single website conversion action.

While the Data Manager API technically doesn't prevent you from connecting multiple different offline feeds (for example, a CRM and a separate internal database) to the same conversion action, we strongly advise against doing so.

We strongly recommend against connecting multiple offline systems directly to the same conversion action. Doing so introduces a high risk of conflicting data from the different uploads and complicates the deduplication process.

Best practice: If you need to consolidate data from several offline systems (for example., Salesforce and a custom internal database), you must merge these datasets before they're brought into Google Ads. This means creating a unified data file or table that Data Manager can connect to as your single additional data source.