If you're a publisher running an iOS app, you've likely faced this dilemma. When a user taps "Ask App Not to Track" in the ATT (App Tracking Transparency) prompt, ad rates for that user drop noticeably from that point on. But you can't show the prompt twice. Apple allows exactly one system prompt per app, and once a user opts out, the only way to reverse it is if they open iOS Settings themselves and re-enable tracking for your app.
That leaves this question. If you could maximize opt-in rates in that single opportunity, how much revenue is actually at stake? We looked at 8 months of impression and revenue data collected through AdControl to quantify the gap.
For iOS publishers, ATT opt-in rate shapes the entire iOS ad revenue curve. Here are the format-by-format gaps we measured, along with the compliant ways Apple allows you to drive opt-ins.
1. Opted-in users deliver about 1.6x the eCPM of opt-out users
Across all ad impressions, ATT-opted users generated an eCPM roughly 1.6x higher (+60%) than opt-out users. Click behavior splits even more clearly. CTR 2.99% vs 1.69%. That personalized ad audiences click more isn't surprising, but from a publisher's revenue perspective the size of the gap is worth pausing on.
This isn't a one-time outlier. From January through August 2026, the monthly ratio held steady between 1.45x and 1.79x. Regardless of season or campaign peaks, ATT opt-in status has settled into a structural driver of CPM.
2. Opted-in users deliver 32% of impressions but 43% of revenue
Reframed from a publisher angle: ATT-opted users account for 32% of total ad impressions but contribute 43% of revenue. One-third of impressions is carrying nearly half of the topline.
Put differently: opted-in impressions are effectively premium inventory sold at a 60% higher rate per impression. Applied to the measured 1.6x gap, each 1-point rise in opt-in rate lifts total revenue by about 0.5%; a 5-point rise, about 2.5%. The exact size depends on your app's format mix.
3. The gap varies significantly by ad format
That "1.6x" figure hides meaningful variation by format. Here's the 8-month cumulative breakdown.
Format | Opt-in eCPM | Opt-out eCPM | Ratio |
Banner | $0.51 | $0.26 | 1.98x |
Native | $0.20 | $0.11 | 1.78x |
Interstitial | $17.98 | $11.76 | 1.53x |
Rewarded | $25.29 | $17.85 | 1.42x |
Banner and native show the widest gap. These formats offer limited premium potential on their own, so from an advertiser's perspective, the "who is this impression served to?" signal weighs more heavily in bidding decisions. Opt-out impressions, stripped of targeting signal, tend to drop into low-CPM remnant campaigns.
The interstitial gap is relatively narrow. Absolute CPMs are already north of $10, and the placement itself is premium enough that advertisers maintain willingness to pay regardless of targeting. Even so, a 1.53x gap means every 1 percentage point of opt-in rate lands hard for apps with a heavy interstitial mix.
Rewarded varies widely by app. The 1.42x in the table is a weighted average across 7 apps, excluding one very large app with a low-CPM inventory profile that would otherwise distort the aggregate. Individual publishers may see gaps larger or smaller than this. If rewarded is a significant part of your mix, verify against your own data.
4. So what can publishers actually do?
What can a publisher do in the face of this gap?
Start with Apple's policy. Apple restricts the ATT system prompt to one per app. Once a user selects "Ask App Not to Track," you cannot show the system prompt again. The only reversal path is a user manually toggling tracking on for your app in iOS Settings.
That doesn't mean publishers are helpless. Apple permits three approaches to driving opt-ins.
- Pre-permission Prompt. A custom in-app screen shown right before the system prompt, explaining why tracking access is needed and what the user gets in return (e.g., "personalized recommendations," "keeps the service free"). Apple's Review Guidelines don't explicitly authorize pre-prompts, but as long as they don't fall into the prohibited patterns below (mimicking system UI, shaming users), pre-prompts are widely used commercially and, when designed well, are known to lift opt-in rates significantly.
- Timing the prompt. Rather than firing it immediately on first launch (before users experience the app's value), delaying until after users have engaged with core features tends to lift opt-in rates. Apple doesn't mandate timing, so this is a lever publishers can freely optimize.
- Route to Settings. For users who already selected "Ask App Not to Track," you can offer a deep link to iOS Settings (
UIApplication.openSettingsURLString) instead of trying to show the system prompt again. Just don't make the nudge frequent or obstructive.
The red lines are spelled out in App Store Review Guidelines 5.1.2(i).
- No incentives or feature gating. "Enable tracking for 100 coins" is off-limits — and so is blocking app functionality or content based on tracking consent status. Original text: "Your app may not require users to enable system functionalities (e.g. push notifications, location services, tracking) in order to access functionality, content, use the app, or receive monetary or other compensation, including but not limited to gift cards and codes."
- No dark patterns. Visually hiding the "Don't Allow" option, emphasizing "Allow" to mislead, or designing pre-permission screens that mimic the system UI — all will trigger rejection in review.
- No forced re-prompt. Attempting to fire the system prompt twice via SDKs or workarounds is impossible both technically and by policy.
5. Bottom line
ATT opt-in is a "one-shot chance" for publishers, but the outcome of that one shot shapes the entire iOS ad revenue curve going forward. The gap the data reveals — 1.6x eCPM overall, 2x for banner and native — is more than enough to justify engineering investment in pre-permission screens and prompt timing optimization.
AdControl provides publishers with reports that break down eCPM by ATT opt-in status, by format, and by period, straight from your own app data. If you'd like to see your app's current gap before adjusting your opt-in strategy, get in touch below.
※ Figures in this article are from AdControl console data across 8 months (January–August 2026) of iOS traffic. Rewarded is reported as the weighted average of 7 apps, excluding one very-large-scale app whose low-CPM inventory characteristics would otherwise distort the aggregate. Restricted traffic (child accounts, MDM-managed devices, etc., 1.9% of impressions) is also excluded from the main comparisons due to low representativeness.