A Quick Guide To Google Merchant Center Supplemental Feeds

Managing all your product data and frequent updates to it on Merchant Center just via your primary feed can be very challenging. That’s because your primary feed can become outdated or may need updates over time in order to continuously improve the visibility of your products on Google Shopping. In such cases, repeatedly editing and reuploading your primary feed may not be feasible or advised for any merchant. 

Then what should you do? Should you never update and optimize your product data? Definitely, not. For such scenarios, you can use Google Merchant Center supplemental feeds. 

Using these feeds, you can easily make quick edits to your product data without updating or changing your primary data source.

How though? 

For that, you will have to continue reading this blog. Through it, we will be discussing a lot of important details related to supplemental feeds that include, but aren’t limited to: 

1. What supplemental feeds are and how to set them up 
2. Their benefits and use cases
3. Best practices for using these feeds

So, then, shall we begin? 

What are Google Merchant Center Supplemental Feeds? 

A supplemental feed is a secondary product data file that is used to enrich or update the information already available in your primary feed. Using these feeds, you can add, update, or even override attributes for existing products without changing the original feed file. 

So, in short, supplemental feeds “supplement” your primary feeds with new or updated product data. 

While these feeds are very useful for making partial updates to your primary product data in GMC, please note that supplemental feeds: 

1. Cannot function on their own. Therefore, you should always have a primary feed uploaded in your GMC, and only then can you add a supplemental feed to enrich it. 
2. Cannot help create new products in the Merchant Center. 

How to Set Up Supplemental Feeds in GMC? 

We will now go through the step-by-step process of setting up supplemental feeds in GMC. 

1. Open your Google Merchant Center account. 
2. Go to ‘Settings’ from the left-hand side menu.
3. Click on ‘Data Sources.’ 

4. Under ‘Product sources’, click on ‘Supplemental sources’ and then ‘Add supplemental product data.’

5. Then you will have to select a method to add product data from these available options: 

• Add product data from a file 
• Use Google Sheets
• Add product data using API 

For reference purposes, we will move ahead with Google Sheets. 

6. Then, you must add your supplemental feed. Now you can either create one from scratch using Google’s template, or you can choose an existing file. For this blog, we will just go ahead and create a new file from scratch using Google’s template. Here’s the process to follow for the same:   

• When you select Google Sheets as the method to upload your supplemental feed, you will get two options: use a template or choose an existing spreadsheet. 
• Click on ‘Use template.’

• Google will then create a supplemental feed template in Google Sheets for your account. This Supplemental feed template will have an exactly similar structure to your primary feed file. It will have similar-looking header columns, attribute names, etc. 

• Adapt your feed to this template’s structure. This means keep the product ID as is, and make required edits to all attributes that you want. 
• If you want to add any other new optional attribute to the file, then add a column header for it and add its value. 
• Once your supplemental feed is ready in Google Sheets, return to your Merchant Center interface.  

7. Edit its schedule frequency. As a pro tip, we recommend keeping it to ‘Every 24 hours.’ That will allow Google to retrieve any update to your product data, whether minor or major, on a daily basis, ensuring that your product data is always up to date. 

💡Scheduled fetches allow Google to retrieve information from your Google Sheet or server automatically at regular intervals. This ensures that your product data information is always up-to-date in Merchant Center.

8. Click on ‘Continue.’
9. Then you will have to add a feed label. It will help you categorize and better identify your products in ad campaigns. 

Note: Google recommends that you should only use uppercase, digits, hyphen, or underscore for feed labels.

10. Select a primary data source (primary feed) for the supplemental feed. 

11. Click on ‘Create data source.’

That’s it. Your supplemental feed would be created. If you want, then you can further customize some of its advanced settings, such as encoding, quoted fields, etc. 

Use Cases of Google Merchant Center Supplement Feeds 

Now, let’s look at the different scenarios where using supplemental feeds can be beneficial. 

Fix Product Disapprovals or Data Feed Errors

You can easily fix data feed errors related to invalid or incomplete product information with supplemental feeds. 

For example, if Google flags several items of your feed with the “Missing color for product variants” GMC error, you don’t need to edit or re-upload your main feed. Simply create a new feed file in Google Sheets, copy the ID of all products from the primary feed, add the color attribute for all the flagged variants, and upload it to GMC as a supplemental product data source. 

Google will process and verify the new data, and apply it, if everything checks out. This simple method helps get your disapproved products approved without even touching your primary data source on GMC.

Optimize Titles and Descriptions 

Strong, well-optimized product titles and descriptions play an important role in boosting the visibility of your listings across Google Shopping. If the values for any of these attributes are very generic or not up to the mark, you can easily update them using supplemental feeds.

Using these feeds, you can:

• Add relevant keywords to both titles and descriptions
• Highlight USPs of your items to make your listings stand out
• Ensure that both title and description attribute values are fully compliant with Google’s feed requirements

This approach is especially helpful for those merchants who want to promote their Shopify or BigCommercewhere products on Google Shopping. That’s because the default product data from these e-commerce platforms is never fully aligned with Google’s requirements. And by optimizing product data through supplemental feeds, merchants can easily boost product visibility, click-through rates, and overall ad performance.

Note: Use AdNabu’s Shopify Metaobject feature to ensure your data is accurately mapped to the correct Google feed attributes.

Add Custom Labels 

Supplemental feeds can also be helpful whenever you need to add or modify custom_label attribute values for products in your feed. 

💡Custom labels (0-4) are labels that you can assign to products in order to organize bidding and reporting in Shopping campaigns.

So, during seasonal sales or promotions, you can tag specific products with labels like “Summer2025” or “Clearance” using these feeds. 

Once these labels are applied, you can easily segment your Shopping campaigns and adjust their bids, targeting, etc., in a much more effective manner. 

Adjust Sale or Promotion Prices

During sales or promotional events, you may have specific requirements that require you to override or discount the original prices of items in your feed immediately. In such cases, the tool or integration you are using for your e-commerce store may or may not be helpful. 

So, even to handle such scenarios, you can use supplemental feeds. Simply add the ‘sale_price’ and ‘sale_price_effective’ attributes for all the required items. This will help you lower their prices on a temporary basis. Once the sale period is over, you can either update your supplemental feed or even remove it. 

Pro tip: Always ensure that the price of an item in your feed, website, structured data, and all other verifiable sources is the same. If there are inconsistencies, Google may disapprove your products with the ‘price mismatch’ error in GMC.

Include or Exclude Destinations For Products

If you want to include or exclude products from participating in certain types of advertising campaigns, then you can use supplemental feeds for that as well. 

All you need to do is add any of the two ‘included_destination’ and ‘excluded_destination’ attributes for the required products, and upload the supplemental feed on GMC. 

Once those attribute values are applied to the selected products, they will either start or stop showing in the respective campaign types. 

So, for example, if you have certain items for clearance in your inventory, then you can easily exclude them from Shopping ads using the excluded_destination = Shopping_ads value. This will help ensure that you don’t spend your ad budget on low-value items. At the same time, if you have certain high-margin items that you want to showcase across YouTube Shopping, Buy on Google listings, and other placements, you can submit those values using the included_destination attribute. 

This way, these feeds can be used strategically to control where your products appear and maximize the value of your ad budget. 

Benefits of Using Supplemental Feeds

Now, let’s look at the benefits of using supplemental feeds in detail. 

Fill Missing Data and Attributes Seamlessly

With Supplemental feeds, you can easily add missing or optional attributes to optimize your Google Shopping feed and boost its performance. You can include attributes like GTIN, MPN, or even Google Product Category and enrich your listings with more details.

Detailed listings always help shoppers find your products more easily, see accurate information at all times, and make confident purchase decisions.

Improved Ad Performance 

By enriching your product data with supplement feeds, you can boost the performance of your ads. Detailed and accurate product information (such as keyword-rich titles, comprehensive descriptions, etc.) helps Google match your products to the most relevant search queries. This results in improved CTRs, increased conversions, and enhanced overall campaign performance. 

Make Quick Updates to Product Data in Bulk

Supplemental feeds are very helpful in making accurate bulk updates to product data on GMC. This agility can be helpful in making time-sensitive changes, such as quickly updating the sale prices or availability of multiple items during promotions, etc. 

Pro tip: Instead of using supplemental feeds, we recommend using a feed management software to make quick updates (whether minor or major) to your product data. These tools offer AI feed optimization capabilities, reduce the scope of manual errors, and sync your product data updates to GMC instantly.

Zero Downtime For Listings

With supplemental feeds, you can ensure that your primary feed and its data get updated without actually making any changes to the file. This is important as it ensures that your live product listings continue to perform without any disapprovals and downtime. 

Best Practices for Creating and Setting Up Supplemental Feeds

To get the most out of supplemental feeds and avoid common pitfalls, we recommend following the following best practices: 

Ensure Product ID Consistency 

Always ensure that the product IDs of items in your supplemental feeds exactly match those in your primary feed. This means letter case, prefixes, or suffixes, etc., should all be the same. 

Even a minor discrepancy (such as an extra space or different letter casing) will lead to mismatches and disapproval of your products. 

Pro tip: When creating your supplemental feeds, we recommend copying or exporting the product IDs directly from the primary feed file (source). This will help prevent mismatches and errors that hamper your advertising efforts.

Only Use Supplemental Feeds for Necessary Changes

While supplemental feeds are powerful and help make partial updates to your feed, don’t overuse them for minor tweaks on a handful of products. If only one or two items in your feed need updates, then consider updating your primary feed file at the source or creating a feed rule. 

Avoid creating a new secondary data feed file, as it will require additional maintenance. 

Maintain Data Quality and Consistency

Treat your supplemental feed with the same priority as your primary feed. Ensure that you follow Google Shopping feed requirements and add valid attributes and their values for all items. 

For example, if you are adding product highlights to your feed, ensure that you only cover the product through those highlights and refrain from sharing any other promotional or salesy information. Moreover, the language in those highlights should be professional and grammatically correct. Additionally, you should share 4-6 product highlights, as this is what Google recommends. 

Such proactiveness in terms of maintaining accuracy and compliance throughout your supplemental feed will ensure that your product data is error-free and compliant with Google’s policies. As a result, your listings will have better visibility and deliver stronger performance.

Monitor Product Data Changes Proactively 

After uploading your supplemental feed in GMC, ensure that you check the “Needs attention” tab for all products. This helps you track if: 

1. If any GMC errors or issues that were earlier flagged for some items have now been resolved with the edits made through the supplemental feed, or;
2. To check if the product updates have been applied properly and that no new issues appear after changes. 

Regular monitoring is essential, as it helps ensure that your advertising efforts never come to a halt. 

Conclusion and Key Takeaways 

Supplemental feeds make it easier to update, optimize, and manage your product data without touching your main feed. They help you keep your listings accurate, compliant, and optimized for performance on Google Shopping.

The key takeaways from this article include:

• Supplemental feeds are secondary product data sources in Google Merchant Center. They are used to enrich or update your primary feed with new or corrected product information. These feeds cannot work on their own and only function alongside an existing primary feed.
• Setting up supplemental feeds in GMC is quick and simple. You can use Google Sheets or upload a file to update your primary feed’s data. 
• While creating a supplemental feed, always make sure that product IDs match exactly with those in your primary feed for the updates to apply correctly.
• Supplemental feeds are useful in many situations. You can fix product disapprovals, enhance titles or descriptions, add custom labels, adjust sale prices, or include or exclude products from certain campaigns. They allow you to make these updates without disrupting your main feed.
• Using supplemental feeds helps improve ad performance and visibility. They enable quick bulk updates, minimize downtime, and keep your product data accurate and compliant with Google’s requirements. This flexibility saves time and enhances overall campaign efficiency.
• Always maintain data quality and consistency across your feeds. Use supplemental feeds only for necessary updates and monitor changes regularly in GMC. This ensures your product data stays clean, compliant, and fully optimized for better results.

Good luck! 

FAQs

1. What is a supplemental feed in Google Merchant Center?

A supplemental feed is a secondary data file in Google Merchant Center. It helps update, enrich, or correct the information already available in your primary feed. Supplemental feeds can’t work on their own. They only modify existing products and can’t be used to create new ones.

2. How to add a supplemental feed in Google Merchant Center?

To add a supplemental feed, log in to your Google Merchant Center account and go to Settings → Data Sources → Add Supplemental Feed. You will then see three options to add product data. Those include, from a file, using Google Sheets, or through the Merchant API.

Select a method and either upload the file or add the data source name (in case of APIs). Once done, continue further and create the data source. That’s it. Your supplemental feed will be created successfully, and Google will process and apply your updates automatically.

3. What’s the difference between a primary feed and a supplemental feed? 

A primary feed is your main product data source. It contains all your product details like titles, prices, and images.

A supplemental feed is used to enrich or update that data. It depends on the primary feed to function and can’t add new products. In short, the primary feed builds your listings, while the supplemental feed improves them.

4. Can supplemental feeds help with the ‘Expiring items’ error in GMC?

No, supplemental feeds can’t fix the “Expiring items” error in GMC. This error appears when Google hasn’t received a full product update within 30 days. Since supplemental feeds only send partial updates, you must reupload or refresh your entire primary feed to resolve it.

5. Can I use multiple supplemental feeds for a primary data source in Google Merchant Center? If yes, how will edits apply, and which one will take precedence?

Yes, you can connect multiple supplemental feeds to the same primary data source in Google Merchant Center. When multiple supplemental feeds contain updates for the same attribute, Google applies them in order of priority. The feed added last will take precedence over the earlier ones.

In simple terms, if two supplemental feeds update the same product attribute, the data from your latest supplemental feed will override the previous ones.