In the UK, I have spotted an offer ad. It is appearing for desktop searches of ‘adwords’. The offer extension replaces the site links and will allegedly only appear for the number 1 ranked ad. There is additional room for explanation of the offer, up to 60 characters to explain the deal, expiry, limitations and restrictions. This is how Google can monitor relevancy.
On clicking, it goes through to a Google discounts page with the voucher which can then be saved to a Google discounts account for later use or immediately printed.
The extension probably cannot be combined with site links since it clicks through to a Google discounts landing page and presumably does not need to be the same as the ad’s destination domain URL. I wonder if Google will allow click through to advertisers own sites.
The popularity of these offer ads will be dependent on uptake and willingness to use Google discounts. Advertisers will need to host offers and discounts on the Google platform rather than promo codes and discounts on their site/other ad formats.