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Microsoft CAPI takes 90-day-old events

Microsoft's Conversions API guide now says an event's timestamp can be up to 90 days old, up from 7. Your conversion goal's attribution window still decides what gets credit.

Jerry Quin2 min read3 sources

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The short answer

What changed

Conversions API (CAPI) is "Microsoft Advertising's server-side solution for sending conversion and customer interaction data directly from an advertiser's systems to Microsoft Advertising." Its developer guide, last updated Oct 29, 2026, now says each event's timestamp "must be within the last 90 days." The limit was 7 days.

Who has it

Anyone sending events to Microsoft Advertising through CAPI. The guide doesn't limit the change to certain accounts or markets, and it doesn't say whether partner connectors have changed their own settings.

What I'd do this week

My advice, not Microsoft's: if deals close in your CRM weeks after the click, check that your conversion goal's window covers that delay before you send older events.

What the guide says now

The eventTime field on each CAPI event has a new limit. The line reads: "eventTime must be within the last 90 days. For optimal measurement, we recommend sending events as close to real time as possible."

Before the Oct 29 update, the same line said "eventTime must be within the last 7 days," and the sample error message in the guide said 7 days too. Both now say 90.

That puts CAPI in line with offline conversion imports in the Bulk API, where "the date and time must be within the last 90 days."

The catch: your attribution window

A 90-day limit doesn't mean a 90-day-old event gets credit. The guide adds a note: "The 90-day event submission limit is separate from the conversion goal's attribution window. Events must fall within the configured attribution window to be eligible for attribution."

So the conversion goal still decides what counts. If its window is shorter than the gap between click and sale, the event can arrive and still not be attributed.

For what CAPI does and the partners you can set it up through, see our Oct 28 post on CAPI going generally available.

What I'd do this week

These are my suggestions, not steps from Microsoft.

  1. Measure your lag. Look at how long your CRM deals or offline sales usually take to close after the first click. That number tells you whether the old 7-day limit was cutting you off.
  2. Check the goal's window. Open the conversion goals you plan to feed through CAPI and compare their windows with that lag.
  3. Keep sending fast. Microsoft still recommends sending events as close to real time as possible. Use the longer limit for sales that truly close late, not as a reason to batch everything.
  4. Keep event IDs stable. If you resend or retry older events, reuse the same eventId for the same conversion. The guide says this supports deduplication and avoids double counting.

Jerry Quin

Jerry Quin is the pen name of a paid media practitioner who has managed Google Ads accounts at an agency for 10 years. He writes about Google Ads, Microsoft Ads, ChatGPT Ads, and the rest of paid media and digital marketing, from what's rolling out to what he'd actually do about it.

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