As you see in the picture below, US Airways is offering up to a 50% bonus when you share US Airways miles in the month of July. This doesn’t mean you can share for free and get a bonus. It basically means you are getting a discount on the regular share pricing. What’s that mean? Miles can be shared for $0.01 per mile plus a processing fee (“processing fee”) of $30 and a tax of 7.5%.
So, in English, that means that if you transfer 50,000 miles, your friend/family member/random person will receive 75,000 miles and it will cost you $569.75, or 2.279 cents per mile. They were just running a promotion with a 100% bonus for purchasing miles — it cost about 1.8 cents per mile. That promotion seems to appear a couple of times a year.
Unless you absolutely need miles (or are looking to transfer out a handful of orphan miles into someone else’s account), I’d hold off on this one.