Why it matters
A full ISO 8601 value in markup disambiguates a visible date whose local time zone Google might not detect correctly, and date formats also differ between countries; this matters for event extraction and wherever the date must be exactly right, such as sale periods. Google accepts a date without a time where the time is not known: its Event guide asks for 2019-08-15 rather than an invented hour.
How to meet it
Output values such as 2026-11-27T19:30:00+01:00 for startDate, uploadDate, validFrom, priceValidUntil and similar properties, generated from the same timestamp as the visible date and with the correct UTC offset. Where the time is unknown or irrelevant, write the date alone (2026-11-27).
How to test it
The Rich Results Test shows the parsed dates, and a unit test asserts that every DateTime value has an offset (+01:00 or Z) and that date-only values are YYYY-MM-DD, used only where the time is unknown or irrelevant.
How Regensbot covers it
Decided from one URL.
An audit reads the response, the headers, the HTML, robots.txt, the sitemaps and the structured data, and the finding shows the evidence it saw.
Sources
Google documents02
- 01Event (Event) structured dataGoogle Search Central (opens in a new tab)
- 02Merchant listing (Product, Offer) structured dataGoogle Search Central (opens in a new tab)
Claims in the knowledge base05
- D2-C466ConsistentWhat is Structured Data and why we need it on the internet.Said on stage
- D2-C463UndocumentedWhat is Structured Data and why we need it on the internet.Shown on screen
- D2-C610UndocumentedFocusing on Internationalisation and LocalisationSaid on stage
- D2-C468n/aWhat is Structured Data and why we need it on the internet.The author's interpretation
- D2-C836SourceWhat is Structured Data and why we need it on the internet.Google's documentation
Claim IDs refer to the Search Central Live 2026 knowledge base. The knowledge base (opens in a new tab)
- Consistent
- Google's documentation supports it without stating it.
- Undocumented
- Said or shown at the event, not in the documentation.
- Source
- The claim is the cited document itself.
- n/a
- Nothing to verify: a quotation, framing, opinion or analysis.