iOS 14.5 Attribution

Definition

iOS 14.5 Attribution: iOS 14.5 (released April 2021) introduced App Tracking Transparency, requiring Apple users to explicitly opt in to ad tracking. It cut Meta's attribution signal by 30-50% and reshaped DTC measurement.

# iOS 14.5 Attribution Apple's App Tracking Transparency (ATT) framework shipped in iOS 14.5 in April 2021. It forced every app (including Facebook and Instagram) to show an opt-in prompt for ad tracking, and roughly 75% of iOS users declined. For Meta specifically, this meant the IDFA-based deterministic match between ad impression and conversion broke for the majority of its audience, and Meta's reported ROAS degraded measurably. ## Why it matters Pre-iOS 14.5, Meta's pixel could tie almost every iPhone conversion back to an ad impression deterministically. Post-iOS 14.5, Meta built Aggregated Event Measurement (AEM) — a probabilistic, privacy-preserving measurement system with 8-event caps per domain and 24-72 hour delays. The result: platform-reported ROAS became less reliable and [blended ROAS](/glossary/blended-roas) / [MER](/glossary/mer) became the operator's new north star. ## How Admaxxer surfaces it Admaxxer's [Attribution dashboard](/features/capi-match-rate) computes both pixel-reported ROAS (for continuity with Meta Ads Manager) and [blended MER](/glossary/mer) (for the honest number). CAPI is configured end-to-end so you maximize the signal Meta still gets, and [CAPI match rate](/glossary/capi-match-rate) monitoring alerts you when the share of matched events drops. ## Example A brand spending $30,000/mo on Meta saw reported Meta ROAS drop from 4.2x to 2.9x the week iOS 14.5 adoption crossed 50%, even though actual revenue did not fall. The gap was purely signal loss — the campaigns were still working; Meta just could not see it.

Related Terms

Frequently Asked Questions

Does iOS 14.5 affect Google Ads?

Less than Meta. Google uses first-party cookies and signed-in Google accounts heavily, and most Google Ads inventory is on properties (Search, YouTube) where users are logged in. ATT hits Meta and Snap hardest.

Can CAPI restore the pre-iOS 14.5 signal?

No — it closes part of the gap (usually 40-60%) by sending events server-side that the browser pixel missed. It cannot recover users who never consented to tracking in the app.

Will iOS 18 or beyond make this worse?

Apple continues to tighten privacy defaults. Plan for a world where probabilistic and cohort-level measurement is the norm, not deterministic user-level tracking.

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