SKAN 4 postback windows: Apple’s current conversion windows and lock behaviour

Apple’s current StoreKit documentation for SKAdNetwork 4 defines three conversion windows that can yield up to three winning postbacks, with optional lockWindow behaviour that finalises a value early. Measurement leads should map conversion schemas to these Apple values rather than MMP paraphrases. SKAdNetwork 4 generally requires iOS 16.1+ participants as stated in the version 4 release notes; the window lengths themselves are specified on the multiple-conversion-windows article.

What the documentation currently requires

Receiving postbacks in multiple conversion windows (Apple Developer Documentation; markdown body-read 19 September 2026) states:

• The conversion window begins when the user first launches the app.
• First window: days 0 to 2.
• Second window: days 3 to 7.
• Third window: days 8 to 35.
• Apps may update conversion values in all three windows.
• Eligibility for multiple postbacks: ad network signs with SKAdNetwork 4 or later; advertised app calls updatePostbackConversionValue(_:coarseValue:lockWindow:completionHandler:) or updatePostbackConversionValue(_:coarseValue:completionHandler:) in each window.
• Without a lock, the system prepares the postback when the window ends, then sends after a random delay: 24–48 hours for the first postback; 24–144 hours for the second and third.
• With lockWindow enabled, the system prepares immediately on lock, ignores further updates in that window, and applies the same delay bands after the lock.
• Fine conversion-value is relevant to the first postback (tier-dependent); second and third postbacks use coarse values (low / medium / high) when provided. Tier 0 receives only the first postback.

SKAdNetwork 4 release notes state version “4.0” signing, and that advertised apps built with iOS 16.1 SDK or later can register up to three conversions; earlier SDKs only one.

What is recommendation, not Apple law

How a studio packs revenue or tutorial events into fine/coarse values is a schema design choice. Crowding all value into day 0–2 is common industry practice but is not mandated by Apple on these pages.

Who should act, and how

1. Align MMP/SKAN schemas to windows 0–2 / 3–7 / 8–35 from first launch.
2. Decide explicitly whether to lock early for faster postbacks versus waiting for end-of-window.
3. Reserve fine values for window 1; plan coarse-only utility for windows 2–3.
4. Confirm network signatures and app SDK meet SKAN 4 / iOS 16.1 conditions before expecting three postbacks.

Applicability table

Download the applicability table.

Limits of this record

Body-reads Apple StoreKit documentation only. No MMP UI was inspected. Crowd-anonymity tiers affect which fields appear; this record does not predict tier outcomes for a title.

Research checked 19 September 2026. Local draft; human editorial review and byline assignment pending.