Through December 30, 2014, American AAAdvantage and US Airways Dividend Miles are both offering a 30% discount on sharing miles.
The cost to share miles through this promotion is 0.875 cents per mile, factoring in the 30% discount.
On top of that, there’s a $20 per transaction processing charge. AAdvantage accounts less than 14 days old aren’t permitted to participate in the promotion, while Dividend Miles accounts less than 12 days old aren’t permitted to participate in this promotion.
Just to be clear, this isn’t a way to generate miles. AAdvantage and Dividend Miles let you pay a fee to transfer miles between accounts, and this simply gives you a discount on that. This is only useful if you’re trying to “right size” accounts. In other words, if you want to book a one-way first class award between the US and Asia (which requires 67,500 miles) and you have 60,000 miles in one account and 10,000 miles in another account, it could make sense to transfer them so you’d be able to book that.
It’s also worth noting that this isn’t a way to transfer miles between AAdvantage and Dividend Miles. Those accounts will only be merged in the second quarter of next year, but in the meantime you can pay to transfer from AAdvantage to AAdvantage and from Dividend Miles to Dividend Miles.
In the past US Airways’ most lucrative promotions for generating miles were their promotions for sharing miles. They would offer a 100% bonus on sharing miles, which was a way to generate miles for ~1.1 cents each.
Unfortunately I wouldn’t expect that promotion to return in that form, since they raised the cost of sharing miles and made the process of sharing miles more complicated in their most recent version of the promotion.
The only circumstance under which it makes sense to use this promotion is if you need to distribute miles slightly differently between accounts. Some discount is better than no discount.