Technically you can try this trick out with any credit card that you are looking to earn points or miles on. I am focusing on the Starwood Preferred Guest card since their points are the highest valued out there these days. This promo is comparable to some of SPG’s best purchase offers throughout the year (sometimes they offer 35% off which is equal to 2.275 cents per point).
Currently SPG points are 3.5 cents each but Plastiq is currently offering a promotion until the end of the month (February 28, 2017) where they are only charging only 2% (2.5% regularly) for using any American Express card. So instead of paying $35 for 1000 SPG points you would be paying $20 for 1000 SPG points. Some large items to pay for using Plastiq are your mortgage, tuition, or anything really that is a high dollar amount but does not accept credit cards.
FYI, if you use my referral code to sign up for Plastiq you can get 200 fee-free dollars after your first $20 payment: https://www.plastiq.com/cardholder_ui/start?referralCode=601329
Do not use this trick if you are in debt or cannot afford to pay your credit card bill at the end of month. It defeats the whole point of saving money on paying for points.
Starwood Preferred Guest (SPG)
This is pretty much my favorite hotel card especially considering all the amenities that come with it. They are currently having an awesome sign up bonus where you can earn 35,000 SPG points (25,000 points from spending $3,000 in the first three months and 10,000 extra points from spending an additional $2,000 within the first six months). When I signed up it was only 25,000 points so this is really good. If you currently do not have an SPG card I highly recommend signing up. Hit me up and I’ll send you a referral email so I can earn some bonus SPG too!