Paul Hudson from Hacking with Swift has a nice answer on this from 11/28/2021: When it was originally announced, Swift concurrency required at least iOS 15, macOS 12, watchOS 8, tvOS 15, or on other platforms at least Swift 5.5. However, if you’re building your code using Xcode 13.2 or later you can back deploy to older versions of each of those operating systems: iOS 13, macOS 10.15, watchOS 6, and tvOS 13 are all supported. This offers the full range of Swift functionality, including actors, async/await, the task APIs, and more. Important: This backwards compatibility applies only to Swift language features, not to any APIs built using those language features. This means you can write your own code to use async/await, actors, and so on, but you won’t automatically gain access to the new Foundation APIs using those – things like the new URLSession APIs that use async/await still require iOS 15. https://www.hackingwithswift.com/quick-start/concurrency/where-is-swift-concurrency-supported