Delta miles do not expire, regardless of whether or not there is any activity in your Delta frequent flyer account. That's a unique benefit of Delta's frequent flyer program, as a majority of other types of airline miles will expire if you don't meet certain criteria.

Delta Air Lines officially eliminated the expiration of SkyMiles on February 15, 2011, making it the first major U.S. carrier to offer miles that never expire. This change was applied retroactively to all accounts as of January 1, 2011. Before this historic shift, SkyMiles would typically vanish after 24 months of account inactivity. By removing this pressure, Delta effectively turned its loyalty points into a permanent digital currency, a move that was later followed by competitors like Southwest and JetBlue. This policy remains a cornerstone of the SkyMiles program in 2026, allowing members to accumulate miles over decades for "bucket list" trips without needing to constantly monitor their account for qualifying activity. It is important to note, however, that while the miles themselves do not expire, Delta reserves the right to deactivate an account entirely in cases of fraud or if the member remains completely inactive for a period of several years, though such instances are rare for genuine users.