How to Set Up a Supplemental Feed in Google Merchant Center
When to use supplemental feeds, how to create one, and how to fix data gaps in your primary feed without touching it.
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What Is a Supplemental Feed?
A supplemental feed adds or overrides attribute values in your primary feed using the product id as the key. Your primary feed stays unchanged.
Use supplemental feeds when:
- •Your e-commerce platform doesn't export certain attributes (GTINs, google_product_category)
- •You want to add custom_labels for bidding segmentation
- •You need to override prices for specific markets
Creating a Supplemental Feed
- •In GMC, go to Products > Feeds
- •Click + to add a new feed
- •Under feed type, select Supplemental
- •Choose your format (CSV, XML, or Google Sheets)
- •Set the same country and language as your primary feed
Format
Your supplemental feed only needs: id (matching your primary feed exactly) and the attributes you want to add or override.
Example CSV:
- •id, google_product_category, custom_label_0
- •SKU-001, Apparel & Accessories > Shoes, summer_collection
Common Uses
Adding GTINs — If your platform doesn't export GTINs, maintain a separate supplemental feed.
Custom labels — Add custom_label_0 through custom_label_4 to segment products for different bidding strategies.
Sale prices — If your platform doesn't support sale price exports, manage them in a supplemental feed.
Troubleshooting Merges
If supplemental attributes aren't applying, verify: id values match exactly (case-sensitive, no extra spaces), the supplemental feed targets the same country and language as the primary, and it was re-fetched after changes.