SKAdNetwork 4.0: three postbacks, lockWindow, and what to change in your measurement plan

Original article (source): Airbridge - “SKAdNetwork 4.0: Major changes app marketers should know” (Feb 25, 2026)

• https://www.airbridge.io/blog/skadnetwork-4-must-know

Summary

If you only remember one thing about SKAN 4.0: it’s not “more data”. It’s data spread across windows, with new knobs that let you trade completeness for speed.

Airbridge’s explainer is a useful refresher on three practical shifts:

1. Up to three postbacks (instead of one), tied to three conversion windows.
2. A new lockWindow option to finalize early and receive postbacks sooner.
3. A new coarse conversion value type (low / medium / high), used when Apple needs more privacy.

1) Three postbacks, three windows (timing matters)

SKAN 4.0 can send up to three postbacks for the winning attribution.

The windows they summarise:

• Postback 1: days 0–2 (48h window)
• Postback 2: days 3–7 (120h window)
• Postback 3: days 8–35 (672h window)

The operational implication: what you can measure, and when you can act, changes. If your team is still trying to run “same-day ROAS” decisions on iOS, the setup (not the dashboard) is the problem.

2) lockWindow: speed up postbacks, but you lose late signals

The lockWindow function lets you end a window early so the system prepares the postback sooner.

That can be worth it if:

• you need faster optimization loops, and
• you can define an early proxy event that correlates with value.

But it’s a real trade-off: lock too early and you stop measuring what happens later in that window.

3) Coarse conversion values (low/medium/high) join the party

Alongside the familiar 0–63 fine-grained conversion value, SKAN 4.0 adds coarse-grained values:

• low
• medium
• high

Apple chooses what you get back based on crowd anonymity (install volume and privacy tiering). In other words: you don’t always get to “configure your way” into granular reporting.

What to do next (tiny wins)

• Pick one early-value mapping per app (e.g., account created, trial started, first core action). Then document it as your default SKAN optimization signal.
• Decide when you’d lockWindow (if ever): write down the specific decision it enables (budget shift, creative winner, channel reallocation) so you don’t lock windows “just because”.
• Update reporting expectations: tell stakeholders that iOS attribution is inherently delayed/aggregated, and align weekly decision cadence accordingly.

Read the original: https://www.airbridge.io/blog/skadnetwork-4-must-know