Update: Some offers mentioned below are no longer available. View the current offers here.The holiday season brings a variety of point and miles earning opportunities. Whether it’s buying gifts for your favorite traveler or using the best credit card for these purchases, you can do many things to boost your account balances before the end of the year. One of the best ways to do this is through airline shopping portals, and one carrier just sweetened the deal for those of you in need of last-minute gifts.If you’ve waited until the last minute for your holiday gift purchases, you may be able to earn bonus United miles.Through December 24, you can earn bonus United miles and take advantage of other discounts when you shop at select retailers through MileagePlus Shopping. These offers are actually grouped into four different categories:Green Monday (generally the second Monday in December and the third largest online shopping day of the year)Free ShippingBOPUIS (Buy Online, Pick Up In Store)eGift Cards & Last Minute GiftsMany also include higher bonus rates for holders of United co-branded credit cards (including the United MileagePlus Explorer Card from Chase, which is currently offering 40,000 bonus miles after you spend $2,000 on purchases in the first 3 months your account is open). Let’s take a closer look and see if any of these bonuses are worth your while.Green MondayAs mentioned above, Green Monday generally refers to the second Monday in December and typically is the third largest online shopping day of the year (behind Cyber Monday and the Tuesday immediately following Cyber Monday). It dates back almost 10 years and started with eBay. Not surprisingly, the online auction site is one retailer with elevated offers for United miles in this first wave.Here’s the full list along with applicable dates:RetailerUsual bonus (cardholder)Usual bonus (non-cardholder)Elevated bonus (cardholder)Elevated bonus (non-cardholder)Applicable dateseBay1 mile/$0.5 miles/$4 miles/$3 miles/$December 11 – 14New Balance5 miles/$3 miles/$10 miles/$10 miles/$December 12 – 14Macy’s2 miles/$2 miles/$6 miles/$6 miles/$December 12 – 14Kohl’s2 miles/$1 mile/$6 miles/$4 miles/$December 11 – 14HP Home2 miles/$1 mile/$4 miles/$2 miles/$December 11 – 14Lenovo2 miles/$1 mile/$4 miles/$2 miles/$December 11 – 14Bose2 miles/$2 miles/$4 miles/$4 miles/$December 11 – 12Omaha Steaks6 miles/$4 miles/$10 miles/$10 miles/$December 11 – 14Aveda5 miles/$3 miles/$10 miles/$8 miles/$December 11 – 14As you can see, many of the merchants are offering a big jump through the end of the day today (12/14), and there are several with much higher earning rates for cardholders. Just be sure you pull the trigger soon! These bonuses end at 11:59pm tonight.Free ShippingSign 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.The second wave includes both bonus miles as well as free shipping offers. Here’s a detailed break-down of the merchants in this category:RetailerUsual bonus (cardholder)Usual bonus (non-cardholder)Elevated bonus (cardholder)Elevated bonus (non-cardholder)Applicable datesBarneys New York2 miles/$1 mile/$4 miles/$4 miles/$December 13 – 14 and 17 – 18Toys “R” Us1 mile/$0.5 miles/$3 miles/$2 miles/$December 13 – 14 and 17 – 18Dell Home2 miles/$2 miles/$4 miles/$4 miles/$December 13 – 14 and 17 – 18The Finish Line4 miles/$3 miles/$8 miles/$8 miles/$December 17 – 18Kmart3 miles/$2 miles/$6 miles/$4 miles/$December 17 – 18Bed, Bath & Beyond2 miles/$1 mile/$4 miles/$3 miles/$December 15 – 18Bloomingdale’s3 miles/$2 miles/$6 miles/$6 miles/$December 15 – 18Nordstrom4 miles/$3 miles/$6 miles/$6 miles/$December 15 – 18Backcountry.com5 miles/$3 miles/$10 miles/$10 miles/$December 15 – 18It’s important to note that the free shipping offers aren’t automatic and across the board. Some require a minimum purchase while others require you to add a coupon code at checkout. Be sure to read the terms and conditions for the individual merchant so you know what to expect when it comes to earning United miles!BOPUISThe third category covers BOPUIS, which stands for “Buy Online, Pick Up In Store.” As we get further and further into December, many sites start posting cutoff dates to receive gift before Christmas via standard shipping, and picking up an item in the store is an easy way to get around that. Here are the details for the merchants in this category:RetailerUsual bonus (cardholder)Usual bonus (non-cardholder)Elevated bonus (cardholder)Elevated bonus (non-cardholder)Applicable datesNeiman Marcus5 miles/$3 miles/$10 miles/$10 miles/$December 13 – 14 and 19 – 20Sears3 miles/$2 miles/$6 miles/$4 miles/$December 13 – 14 and 22 – 24Walmart1 mile/$1 mile/$2 miles/$2 miles/$December 13 – 14 and 20 – 21L.L. Bean1 mile/$1 mile/$2 miles/$2 miles/$December 13 – 14 and 20 – 21Jos. A. Bank5 miles/$3 miles/$10 miles/$10 miles/$December 13 – 14 and 20 – 21Apple Store1 mile/$1 mile/$2 miles/$2 miles/$December 13 – 14 and 20 – 21Cabela’s3 miles/$2 miles/$6 miles/$6 miles/$December 13 – 14 and 20 – 21While this category is geared towards picking up your item(s) in store, it does appear that all purchases should earn the higher bonuses. However, be sure to read the details for each store’s offer before you click through.eGift Cards & Last Minute GiftsThe final category is fantastic for anyone on your list who’s typically hard to shop for. Many retailers restrict your ability to earn bonus miles through shopping portals when you purchase gift cards, but for a few days, select stores are lifting this restriction. These last wave is also great for procrastinators who need last-minute gifts! Here’s a break-down of the participating retailers:RetailerUsual bonus (cardholder)Usual bonus (non-cardholder)Elevated bonus (cardholder)Elevated bonus (non-cardholder)Applicable datesRosetta Stone6 miles/$4 miles/$10 miles/$10 miles/$December 13 – 14 and 22 – 24Home Depot2 miles/$1 mile/$4 miles/$2 miles/$December 13 – 14 and 22 – 24LivingSocial2 miles/$2 miles/$4 miles/$4 miles/$December 16 – 18 and 22 – 24Groupon3 miles/$2 miles/$6 miles/$6 miles/$December 13 – 14 and 22 – 24Restaurant.com10 miles/$6 miles/$15 miles/$15 miles/$December 16 – 18 and 22 – 24Gilt City2 miles/$1 mile/$4 miles/$3 miles/$December 16 – 18 and 22 – 24REI2 miles/$2 miles/$4 miles/$4 miles/$December 16 – 18 and 22 – 24Bergdorf Goodman4 miles/$3 miles/$8 miles/$8 miles/$December 16 – 18 and 22 – 24ExampleHere’s an example of how this promotion can result in some significant earnings. Let’s say that you were planning a purchase at Neiman Marcus. MileagePlus Shopping usually offers you 3 miles per dollar spent at Neiman Marcus, but from December 13-14 and 19-20, this earning rate jumps to 10 miles per dollar spent. You decide to spend an even $1,000 and you use TPG’s recommended card for everyday non-bonus spending: the Starwood Preferred Guest® Credit Card from American Express.Your earnings are thus:$1,000 x 1 point per dollar spent = 1,000 Starpoints (worth $25 based on TPG’s valuations)$1,000 x 10 miles per dollar spent = 10,000 MileagePlus miles (worth $150)Total Rewards = $175Total Return = 17.5%That’s a decent return for your holiday shopping!Maximizing with Gift CardsWhile you typically can’t earn bonus points or miles through shopping portals by purchasing gift cards, I have been able to use retail gift cards to pay for the purchase and earn bonus points or miles.A few retailers in the above table do have electronic gift cards (delivered via e-mail) on Staples.com, including Sears and Macy’s. You also may be able to find additional ones in an actual store, though you also have the option of purchasing them in grocery stores (with a card like the Amex EveryDay Preferred Card from American Express) or gas stations (with a card like the Citi Premier® Card).A valuable redemption (like Lufthansa’s new business class) is that much closer if you take advantage of this promotion!Bottom LineEveryone should be making online purchases through shopping portals as it is, but it’s great to see one airline offering an additional incentive to shop through its site. Even though United significantly devalued its program at the beginning of last year, there are still ways to get a solid value from redeeming MileagePlus miles. This holiday promotion can hopefully put you even closer to that dream trip!Will you be taking advantage of these bonuses through MileagePlus Shopping?