Overview
Advertising tag that tracks browsing behaviour and sends conversion data to Microsoft's ad platform, covering the Bing, Yahoo, and DuckDuckGo syndicated search network. Frequently deployed alongside Google Ads tags but receives significantly less governance attention despite collecting comparable data. Commonly found on regulated organisation websites due to Microsoft's broad enterprise presence, making it a frequent oversight in tag audits that focus primarily on Google and Meta pixels.
Detection capabilities
- Signature count
- 2
- Detection methods
- network
- Property types
- hostnamepathnameparam
Performance impact
Performance Impact
- Script size
- 30 KB
- Requests per page
- 2
Common mistakes
- 1Treating the UET tag as lower-risk than Google or Meta advertising tags when it collects comparable browsing and conversion data requiring the same consent controls
- 2Not enabling Microsoft's consent mode integration, which allows the tag to respect CMP signals and operate in a reduced data collection mode when consent is denied
- 3Deploying UET via a tag manager without restricting it to the advertising consent category, allowing it to fire before the user has granted consent
- 4Failing to review the auto-tagging behaviour that appends click identifiers (msclkid) to landing page URLs, which can persist personal data in server logs
- 5Overlooking UET during cookie audits because Microsoft's first-party cookies (_uetmsclkid, _uetvid) are less well-known than Google or Meta equivalents
Compliance considerations
The UET tag sets first-party cookies (_uetmsclkid, _uetvid, _uetsid) and transmits browsing behaviour to Microsoft servers in the United States. Under GDPR, this requires explicit advertising consent. Microsoft is self-certified under the EU-US Data Privacy Framework, providing a legal basis for transatlantic data transfers. Microsoft's consent mode integration allows UET to operate in a restricted mode when consent is not granted, but organisations must verify this is correctly configured with their CMP. The UET tag should be categorised under advertising consent and blocked until explicit consent is obtained. Organisations in regulated sectors should pay particular attention to the auto-tagging feature, as msclkid parameters in URLs may be logged by web servers and constitute personal data under GDPR.
Related services
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