Should you really include the modification date in your XML sitemap?

Why does Google care about the modification date?

The crawl budget is a limited resource — even for large sites with established authority. Google has to decide which pages to crawl first, and when. The XML sitemap provides directional cues, but not all signals hold the same value.

The <lastmod> tag serves to indicate that a page has been recently modified, which justifies a visit from Googlebot to index the new version. When every URL carries a generic or identical date, this signal loses its discriminating utility — Google can no longer differentiate fresh pages from old ones that have remained unchanged for months.

What exactly is a

Is this recommendation consistent with what we observe in practice?

Yes, largely. Crawl audits regularly show that Google ignores or deprioritizes sitemaps with uniform dates. We see it in the logs: Googlebot visits certain URLs with a frequency that does not match what the sitemap suggests, a sign that it has learned not to trust that signal.

Conversely, on sites where <lastmod> is managed properly — meaning updated only during real editorial changes — we observe a more responsive crawl and faster indexing of new versions. It’s not magic, but it is measurable in Search Console and server logs.

What nuances should we add to this statement?

First, Mueller does not say that <lastmod> is mandatory. He says it’s useful if done correctly, and counterproductive if done haphazardly. If your CMS does not reliably manage this tag, it’s better to omit it entirely rather than sending a noisy signal.

Next, there's a grey area: what constitutes a “real” modification? Changing a comma in a title? Adding a block of related links in a sidebar? Modifying the global footer of the site? [To be verified] Google has never provided a specific threshold. Practical use generally involves only updating <lastmod> for substantial modifications to main content (text, images, videos, structured data).

Lastly, this statement only addresses the effectiveness of the sitemap as a crawling management tool. It does not guarantee that a page will rank better just because it is fresh — freshness is a distinct ranking signal that depends on the query and the type of content.

In what cases does this rule not apply or become secondary?

On a small site of 50 pages, Google crawls everything regularly anyway. The marginal gain of a precise <lastmod> is low — it’s better to focus on content and backlinks. The ROI of the time spent configuring this tag properly is questionable.

Similarly, on a site with a crawl budget already saturated by other issues (massive duplicate content, endless URL parameters, soft 404s, chained redirects), optimizing <lastmod> won’t change much. You first need to clean the structure and eliminate noise signals before tackling the fine-tuning.

What should be done to correctly fill in <lastmod>?

First reflex: audit your current sitemap. Export it, check if the dates are the same for all URLs, or if they correspond to the date the file was generated. If so, you’re in the “generic date” scenario that Mueller points out.

Next, adapt your sitemap generation logic so that <lastmod> reflects the actual last modification date of the content. On WordPress, this can be the