# What is a supplemental feed?

> A supplemental feed is an extra product data source that adds to or corrects the data in your main feed. See when a Shopify store uses one and what to watch.
> Published: 2026-10-14
> Updated: 2026-10-14
> Canonical: https://rabbot.ai/glossary/supplemental-feed/

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A supplemental feed is a second product data source that sits beside your main feed. It carries extra or corrected values for products that already exist, instead of listing the whole catalogue again. Google Merchant Center calls this a supplemental product data source.

## Why it matters for a Shopify store

Merchant Center accepts several sources for one account. Google's help pages say you can add another product source from the Products page and manage sources under Data sources in Settings. A Shopify store often has one main source, built from the catalogue by an app or by the Google channel.

A supplemental source is a place to fix a value without touching that main source. Typical cases are an attribute your theme or feed app cannot output, a corrected identifier, or a label added for a campaign. The main feed stays as it is, and the extra source supplies the values. Check Google's supplemental source guide before relying on a specific rule, such as which source wins when two values disagree.

## How it commonly goes wrong

- The supplemental source and the main source supply different values for one attribute, and nobody knows which one a channel reads.
- A supplemental file keeps an old price or stock value after the store changes it. Google lists a mismatch between product data and landing pages as a cause of item issues.
- A product id in the supplemental file does not match the id in the main feed, so the extra data attaches to nothing.
- A fix lives only in the supplemental file, and the next person who edits the store never sees it.

Google's guidance on disapprovals applies to all sources: incorrect, inaccurate or missing product information can cause disapprovals, limited eligibility and incorrect displays.

## Where Rabbot fits

Rabbot's feed cross-check compares the product data your feeds are built from with what your live storefront shows, and raises a gap as disapproval risk. It does not validate a feed app's own rewrites. Paid plans run the cross-check every day. See [What feed monitoring is](/docs/feeds/what-feed-monitoring-is/).

## Related terms

A supplemental feed adds to a [product feed](/glossary/product-feed/). A common use is correcting a [GTIN](/glossary/gtin/). The goal is usually to clear a [disapproved product](/glossary/disapproved-product/) without a full rebuild.

## Sources

- [Google Merchant Center Help: product data specification](https://support.google.com/merchants/answer/7052112)
- [Google Merchant Center Help: add products and product sources](https://support.google.com/merchants/answer/7439882)
- [Google Merchant Center Help: item issues and disapprovals](https://support.google.com/merchants/answer/2948694)