Google announced last year that they would start requiring advertisers to include the GTINs for products from 50 brands in their Merchant Center product feeds. Recently, Google said that the GTIN requirement will be expanded beyond those 50 brands.
“If you sell brand-name products that are sold by multiple merchants, you should take a close look at the new requirements and double-check that your product data is correct and up-to-date.”
Basically, if you’re promoting products that have GTINs, this is the time you should make sure your feeds are updated to include them.
The date that Google will begin disapproving relevant products that aren’t meeting the GTIN requirements will be May 16, 2016.
GTINs are required when targeting ads in Austrailia, Brazil, the Czech Republic, France, Germany, Italy, Japan, The Netherlands, Spain, Switzerland, the UK or the US.
There have already been item-level warnings by Google in the Diagnostics tab in Merchant Center for products that are miss or have the wrong GTN.
Check out the Merchant Center help page for more information about unique product identifiers that are available.