New MyMcDonald’s Rewards members can enjoy a special treat: a free Big Mac with any $1 purchase when you download the McDonald’s app. This offer is available once for first-time app users through the end of the month at participating McDonald’s locations. Keep in mind that it may take up to 48 hours for the deal to appear in your account, and the offer does not include tax. Take advantage of this great deal and indulge in McDonald’s signature burger for free with your next purchase.