Frequent flyer miles can be redeemed for flight upgrades or free flights if you can manage to accumulate enough of them before they expire. According to an October 2009 press release from AwardWallet.com, the estimated value of current airline miles is around $570 billion but most miles will go unused and expire. If your miles are about to expire or go unused, you can easily donate the frequent flyer miles that you have accumulated to a charity that your airline has partnered with. The available charities vary from airline to airline, but include organizations such as the Red Cross and the Make-A-Wish Foundation.

Step 1 Log in to your frequent flyer account to find out the account balance. While some airline mile donations can be in any increment, there are some airlines that only allow you to donate in certain increments or that have a minimum amount that must be met for a donation.

Step 2 Look for a link in your frequent flyer account for donating your miles while you are logged in. For example, while logged into your Delta SkyMiles account click on “Donate Miles" under “Use Miles." It will take you to the SkyWish Charities page that lists all of the charities to which you can donate your air miles as well as how to do so. Using the Delta SkyMiles example, the only way to donate air miles online as of February 2010 is via the special email address listed on the SkyWish Charities website.

Step 3 Visit the website of the charity to which you want to donate your frequent flyer air miles and look for a “Ways to Help” or “Ways to Donate” link. Click on it to see if they accept air miles as a donation. For example, the Make-A-Wish Foundation's website has “Frequent Flier Miles” as an option on its “Ways to Help” page. Clicking on that link takes you to a page that shows which airline miles they accept as donations. Clicking on the individual airline gives you information on how to donate your air miles. Using Delta as an example again, they give additional ways to donate that are not listed on the Delta website, including by mail and by fax.

Tips Some airlines also allow you to donate air miles over the phone.

According to the IRS, frequent flyer miles donations are not tax deductible donations as they are considered awards or gifts.

Disclosure Leaf Group is a USA TODAY content partner providing general travel information. Its content is produced independently of USA TODAY.

About the Author Jamie Lisse has been writing professionally since 1997. She has published works with a number of online and print publishers. Her areas of expertise include finance and accounting, travel, entertainment, digital media and technology. She holds a Bachelor of Arts in English.