Sitemap lastmod dates

Whether the sitemap dates its entries. Without a lastmod a crawler cannot tell which pages have changed since it last read them.

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<lastmod> is the optional date in a sitemap entry that says when the page last changed in a meaningful way. Google has said it uses lastmod when it is consistently accurate, and ignores the <priority> and <changefreq> fields altogether. Bing relies on it too. On a large site an accurate lastmod is how a crawler finds the hundred pages that changed this week among thousands that did not, instead of recrawling everything.

How SiteScan checks it

The row appears when a sitemap with at least one URL was found. Green shows how many entries carry a lastmod date; amber "Missing" means none does.

How to fix

• Most generators can add it: in WordPress the built-in sitemap and SEO plugins fill it from the post's modified date.
• Use the W3C date format: 2026-10-01 or 2026-10-01T09:30:00+00:00.
• Change it only when the content really changes. A lastmod set to the time the file was generated, identical on every URL, teaches crawlers to ignore it.
• In a sitemap index, date each child sitemap too.

More about keeping sitemaps useful in robots.txt and sitemaps.