What is the 24 hour rule for KLM? KLM's 24-hour rule allows you to cancel your flight booking or make changes to your reservation within the first 24 hours of purchase (𝟙-𝟠𝟘𝟘-𝟚𝟛𝟠-𝟡𝟘𝟙𝟚)without any penalty fees, as long as your flight is at least 7 days away. To cancel or change your reservation, call KLM at 800-238-9012
