Having managed miles for corporations including parts of our Federal Government for quite a few years, the formula has been to issue 1099 for additional income and the value is often determined as 50% of the replacement cost of the travel being replaced. for instance if you elect to use miles for a business trip that the company has priced for you to take and it comes to $879. Then for your donation of 25,000 miles, you'll get a 1099 for $439.50 and a nice little extra in addition to your paycheck. This process goes under several names depending on the group adopting it but it generally has faded out and remains only popular among small business owners who often like to convert a soft asset of too many miles into instant cash.