United is offering a 25% discount on purchased miles through December 31.
The miles do not post instantly, they warn posting can take up to 48 hours though they usually post a bit faster than that.
The minimum purchase is 2000 miles and an account can purchase up to 100,000 miles per year.
The only time this makes any sense is when you have almost enough United miles in an account for an award and need to top off that account (and do not have other, more cost effective ways of doing it).
The deal in effect offers miles for purchase ~ 2.8 cents apiece. That’s still expensive.
United miles are about the most valuable single airline currency out there because of the amazing award availability offered through Star Alliance (best from North American to both Europe and Asia in business class).
But in my view they aren’t worth 2.8 cents. They also aren’t worth orders of magnitude more than other Star Alliance mileage programs like US Airways Dividend Miles (unless and until US Airways merges with American and joins oneworld) and Avianca’s LifeMiles — both of which are currently offering share miles promotions that provide for the purchase of miles much less expensively, about 1.1 and 1.5 cents apiece respectively.
And while you can do better at redemption than 2.8 cents per mile compared to paid travel remember that mileage awards are capacity controlled while cash lets you buy any flight that has open seats, and mileage awards do not themselves generally earn miles or elite status. I am not a buyer at 2 cents or above — except, as I say, to top off an account with most of the miles already in it and for a high value award.
If that situation describes the one you face, then be sure to use this link to make the mileage purchase in order to receive the discount. Though it’s quite possible we see an even cheaper purchase opportunity in the coming months, as I’ve certainly seen them sell miles for less.