Heads up, deal hunters! Office Depot/OfficeMax is running its popular promotion where you get $15 off when you buy $300 in Mastercard gift cards. This deal is reportedly back from January 18th to January 24th, so double-check with your local store to confirm it's live. You're limited to one deal per household or business, and it's only valid in-store. Why should you care? This is an easy way to rack up rewards! Buy the gift cards, use a credit card that earns bonus points at office supply stores (like the Amex Business Gold with its $20 credit or a card earning a high percentage back), and then use the gift cards for your everyday spending or to meet minimum spending requirements on new credit cards. Keep in mind that MetaBank (the gift card issuer) increased their fees, so factor that into your calculations. You might also have a Chase Offer or other bank offer for an additional percentage back, making this deal even sweeter.