Microsoft Advertising notified advertisers in early June that it will update its UTM auto-tagging system on September 2, 2026, replacing a universal tagging approach with format-specific parameters for each campaign type. No advertiser action is required; the new tags apply automatically to all accounts with auto-tagging enabled.
The practical problem being fixed is one paid teams running Bing campaigns have lived with for years. Under the current system, every non-search format arrives in Google Analytics 4 tagged as Paid Search, sitting in the same channel bucket as keyword-triggered text ads. A display placement on the MSN network priced per thousand impressions and a keyword campaign priced per click land under that one label, despite behaving nothing alike. Every aggregate a team reviews, including click-through rate, conversion rate, and cost per acquisition, then blends two fundamentally different traffic types.
According to PPC Land, which first reported the advertiser notification, the September update will give each format its own combination of utm_source, utm_medium, and campaign suffix values. Search campaigns keep utm_source=bing and utm_medium=cpc, mapping to the Paid Search channel in GA4. Audience Ads shift to utm_source=msads and utm_medium=cpm, routing to the Display channel. Shopping Ads carry utm_source=msads and utm_medium=cpc with a shopping suffix, landing in Paid Shopping. Video campaigns use utm_source=bing_video and utm_medium=cpc for Paid Video. Performance Max takes utm_source=msads and utm_medium=crossnetwork with a cross-network suffix, aligning with GA4’s Cross-network channel definition.
The Cross-network mapping deserves specific attention. GA4 introduced that channel grouping to handle automated formats that serve across multiple placement types, and it matches the same utm_medium=crossnetwork value that Google Ads already uses for its own Performance Max campaigns. Analytics platforms that have not configured the Cross-network channel group will route Microsoft’s Performance Max traffic to an unknown bucket instead, which means the fix partially fails in under-configured environments.
One practical risk teams should verify before September: custom UTM parameters set through URL templates may interact in unexpected ways with the auto-applied values once the new format-specific tags arrive. The shopping suffix, for instance, is a platform-appended campaign-level parameter, not the advertiser-set utm_campaign value. Advertisers who have built their own campaign URL templates should test how these interact with the updated auto-tagging behavior before the cutover date.
The structural change also creates a data continuity problem worth flagging now. September 2 will mark a hard break in historical channel data for most accounts. Audience Ads traffic that currently reports as Paid Search will move to the Display channel from that date forward. Performance Max traffic shifts to Cross-network. Any report comparing channel performance across periods that span September 2 will show what looks like a decline in Paid Search and the appearance of new channels, even though nothing about campaign delivery actually changed. Annotating September 2 in GA4 and any other analytics platform before the change takes effect will prevent those trend lines from being misread.
Teams running Microsoft Advertising campaigns on Adobe Analytics or any platform other than GA4 should validate that their channel definitions and processing rules can correctly interpret the incoming utm_source=msads and utm_medium=crossnetwork values. Microsoft’s notice, per PPC Land, tells advertisers on other platforms to ask their analytics vendor how to handle the new values, but leaving that conversation until after September 2 leaves no time to fix misclassification.
The update fits a direction Microsoft has taken with its automated campaign types: making them auditable inside third-party analytics rather than only within its own dashboards.
Reported by PPC Land on June 6, 2026, based on Microsoft Advertising’s notification to advertisers about the September 2 UTM auto-tagging update.
