Yes, it is perfectly legal to buy airline miles, but you must distinguish between "buying from the airline" and "buying from a third-party broker." Almost all major airlines (like Delta, United, and British Airways) have official programs where you can buy miles directly from their website. This is a safe, legal, and instant way to top up your account for a specific reward flight. However, buying or "selling" miles through third-party brokers or "mileage black markets" is a different story. While not a "criminal" act in most countries, it is a violation of the airline's terms and conditions. If an airline detects that you have purchased miles from an unauthorized source, they have the right to freeze your account, cancel your tickets, and seize all your accumulated points without compensation. In 2026, airlines use sophisticated fraud-detection algorithms to monitor for suspicious transfer activity. Therefore, while buying miles is legal, you should always do so through the airline's official channels to ensure your hard-earned rewards and your future travel plans remain secure.