Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.One of the best ways to get bonus miles without actually flying is through airline shopping portals. And with the holiday shopping season upon us, now’s a better time than ever to make sure you take advantage of the opportunity to earn bonus points and miles for purchases that you’d be making anyway.To sweeten up the bonus mileage earning this season, United Airlines is offering a one-day elevation on select merchants. With each of the below merchants, you’ll earn 15 miles per dollar for today only.NikeSaks OFF FiftheBagsNeiman MarcusBoseBackcountryHarry & DavidSunglass HutRosetta StoneSephoraJos. A. BankSur La TableShutterflyNew BalanceShoebuy.comThe 15 merchants will offer customers 15 miles per dollar spent through 11:59pm ET today, December 5, 2016. To take advantage, make sure you do your shopping directly through the United MileagePlus Shopping portal. The elevated bonus could really add up with these retailers. For example, if you’re making a $350 purchase with Neiman Marcus, you’ll earn a total of 5,250 MileagePlus miles. Based on TPG’s most recent valuations, those miles are worth about $79 — pretty good for a purchase you were already planning on making!To ensure that you get the miles you’re entitled to on this one-day elevation, there are some important portal-specific rules that you should follow. For example, be sure you make the purchase directly through the link from the portal and don’t navigate away from that window when you place your order. If you’re looking to take advantage of these elevations, act quick, as they end tonight at 11:59pm ET.