Two weeks remain in January. This is especially important for cardholders of the personal/consumer Platinum Card from American Express, the Business Platinum Card from American Express, and personal/consumer American Express Gold Card.

Why? Because this month is when existing cardholders may change their preferred airline for their card’s (or cards’) annual airline incidental credit. (New cardmembers applying later in the year can select their airline upon receiving their card.)

Which cards get how much credit each year? Does every airline participate? What charges are eligible? Let’s tackle those questions!