Head over to Groupon to score 20% Cash Back on In-Store Starbucks Purchases for one week! To claim this offer, click “Claim” to link the deal to your eligible credit cards for free and then use it for your purchases at Starbucks. The 20% cash back will then be awarded on your credit card statement. Once you claim it, it will be valid for seven days with a limit of $1 cash back per transaction and one transaction per day. Get the deal here!