App Tracking Transparency requires an app to ask permission before linking data collected inside it with data collected by other companies’ apps or websites, for advertising or for sharing with data brokers. Apple has published exactly what that permission does and does not cover, and the two are narrower than the feature’s name suggests.
The prompt has applied since iOS 14.5 and iPadOS 14.5, and it still governs every app on iOS 27, which arrives Monday, September 14. Apple’s support article on the subject, and its developer documentation for the App Tracking Transparency framework, describe the mechanism in specific terms rather than general ones.
Key facts, as Apple documents them
| Item | What Apple publishes |
|---|---|
| In effect since | iOS 14.5 and iPadOS 14.5 |
| What triggers the prompt | Linking data from the app with data collected by other companies’ apps, websites or offline sources, for advertising or data-broker sharing |
| User choices | Allow, or Ask App Not to Track |
| If declined | The app cannot access the device’s advertising identifier (IDFA) or use other identifiers, such as an email address, for the same purpose |
| App functionality | Apple states the app’s full capabilities remain available either way |
| Where to review it | Settings, then Privacy and Security, then Tracking |
What counts as tracking, in Apple’s own wording
Apple’s developer documentation defines tracking as linking data collected from an app with data collected from other companies’ apps, websites or offline properties, for the purpose of targeted advertising or advertising measurement, or sharing that data with a data broker. That is a specific test, not a general description of data collection. An app can still gather information about how it is used without that activity meeting Apple’s definition of tracking.
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Apple’s guidelines also state one documented exception: when data from an app is linked with third-party data solely on the user’s device, and is not sent off the device in a way that could identify the user or device, that linking does not require the tracking prompt. Apple has published this as an on-device carve-out. It has not published a public list of which apps rely on it or how often.
A separate setting governs Apple’s own advertising
App Tracking Transparency governs third-party apps. Apple documents a different, separate control for its own advertising in the App Store, Apple News and Stocks, called Personalized Ads, found under Settings, then Privacy and Security, then Apple Advertising. Apple’s support pages describe the two as distinct systems rather than one setting with two names.
| App Tracking Transparency | Personalized Ads (Apple Advertising) | |
|---|---|---|
| Covers | Third-party apps tracking across other companies’ apps and sites | Apple’s own ad delivery in the App Store, Apple News and Stocks |
| Where it appears | A prompt inside each app, then Settings > Privacy and Security > Tracking | Settings > Privacy and Security > Apple Advertising |
| Default state | Apps must ask; nothing happens until the user answers | Apple states this can be turned off at any time |
Where permissions are reviewed after the prompt
- Settings, then Privacy and Security, then Tracking, lists every app that has requested permission and lets a user grant or withdraw it at any time.
- Apple’s App Privacy Report, a separate feature under the same Privacy and Security menu, records how often apps access data such as location, photos, camera, microphone and contacts over the past seven days.
- Withdrawing permission after initially allowing it takes effect immediately, per Apple’s documentation, though it does not undo data already linked before the change.
The iPhone 18 Pro and Apple Watch Series 12 both run software where this same tracking prompt and the same settings path apply; Apple has not published a version of App Tracking Transparency that behaves differently on newer hardware.
What Apple has not said
Apple has not published how many apps rely on the on-device linking exception, how often users choose Allow versus Ask App Not to Track, or what happens to data an app already collected before a user withdraws permission. It also has not published whether App Tracking Transparency changes in scope under iOS 27 beyond continuing to apply.
As of Saturday, September 12, 2026, the settings path and the definitions above are what Apple’s own pages state; anyone checking their own tracking permissions can do so today under Settings, Privacy and Security, Tracking, ahead of Monday’s iOS 27 rollout.