When Do Air France & KLM Flying Blue Miles Expire?

Air France – KLM Flying Blue has an overly complicated mileage expiration policy because it has different expiration policies for miles earned from flying and miles earned from other means, including transferring credit card points.

You can reset the expiration of any miles in your account for another 24 months by (1) taking another flight on Air France, KLM, or partner airlines and crediting those miles to Flying Blue, (2) making a purchase with a Flying Blue credit card, or (3) if you have Flying Blue Silver, Gold, or Platinum status.

Other mileage activity such as transferring miles, hotel stays, rental cars, and purchasing miles will not extended the life of miles earned via flying, but it will extend the miles you earned via those other non-flying activities (transferring miles, rental cars, etc.). 

For example, imagine you had 50,000 miles in your account from flying and 50,000 miles in your account from non-flying activities that are due to expire in a month. If you take a flight and credit it to Flying Blue, then the expiration of all 100,000 miles get extended. However, if you were to transfer new points into Flying Blue, then only the expiration for the 50,000 miles from non-flying activities would reset.