Though an end date for the promotion isn't specified for the US, in the UK, shoppers must use the credit before 28 July, 2019.
Don't forget to sign up for Amazon Prime if you're not already a member to make the most of Prime Day discounts. Get the 30-day free trial now.
The plug-in is available for Chrome, Firefox, Microsoft Edge, Safari and all major browsers. It allows you to compare prices against Amazon's and add items to your Wish List no matter where you are on the web. It's especially useful if you're working on a Wedding List.
Don't forget there are tonnes of Summer Sales going on right now across major UK retailers in competition with Prime Day, and you can see them all right here.