Should you still bother filling in the lastmod tag in your XML sitemaps?

Gary Illyes is direct: Google does not take the lastmod tag into account in XML sitemap files. The reason given? Its chronic unreliability.

Many sites update this tag automatically with every republication, recrawl, or cosmetic modification — while the actual page content remains identical. As a result: Google receives thousands of parasitic signals and decided to simply ignore this data.

Why does this tag create problems for Google?

The issue stems from widespread poor implementation. Popular CMSs (WordPress, Drupal, Magento) often update lastmod whenever you touch any metadata, republish an article, or modify a single pixel in the sidebar.

Google crawls billions of pages. If the tag constantly lies, it becomes counterproductive: the bot wastes time recrawling unchanged pages at the expense of new critical URLs. Gary Illyes' team made the call: we're not using it anymore.

Bing still uses lastmod — why this divergence?

Bing takes a different approach to crawl budget. With a smaller index and proportionally fewer resources, Microsoft's search engine can afford to take risks on imperfect signals.

Or to be honest — Bing simply hasn't yet been polluted enough by millions of misconfigured sitemaps to abandon this data. But Gary doesn't say that explicitly.

What should you take away for your sitemaps?

• Google completely ignores the lastmod tag for years now
• Bing continues to use it as a freshness signal
• If you're targeting non-negligible Bing traffic (B2B, certain verticals), keep it clean
• For Google, focus on actual update frequency rather than sitemap metadata
• Don't waste time perfecting a tag that Google doesn't read

Does this statement really change anything for us?

Not really. Most experienced practitioners already knew that lastmod was a weak signal for Google — this official statement just formalizes what we've been observing for years.

What's interesting is that Gary justifies this position through a data quality problem, not a technical limitation. That means if CMSs were to implement lastmod correctly tomorrow, Google could reconsider. But realistically? That will never happen.

Should you remove this tag from your sitemaps?

No. First, because Bing uses it, and depending on your sector (finance, B2B tech, corporate), Bing can represent 5 to 15% of organic traffic. Not negligible.

Second, because removing a tag requires development, testing, and will get you absolutely nothing from Google. Better to leave it — as long as it's not generating massive false positives that could disrupt your internal monitoring.

What are the real priorities for your sitemaps?

If Google doesn't read lastmod, what does it read? The structure of your URLs, their frequency of appearance in the sitemap, and especially the consistency with your robots.txt. [To verify]: we have no official confirmation that Google uses the sitemap to prioritize crawl — but field observations show that a well-segmented sitemap often accelerates indexation.

Another point: don't put 50,000 URLs in a single XML file. Segment by content type, by language, by date. It helps Google understand your site's structure — and it helps you monitor what's actually being crawled.

What should you concretely do with the lastmod tag?

If you're optimizing solely for Google: don't touch anything. Let your CMS generate whatever it wants, it will have no impact. Don't waste time manually correcting dates for a search engine that ignores them.

If Bing matters to your strategy (English-speaking markets, B2B, corporate): make sure lastmod reflects a genuine content modification. Not a template change, not an automatic republication, not a sidebar update.

How do you verify that your lastmod is reliable?

Crawl your sitemap with Screaming Frog or an equivalent tool. Compare lastmod dates with the actual history of your modifications (Git, CMS logs, Internet Archive). If 80% of your pages have been "modified" last week when you haven't touched anything, you have a problem.

Also audit your CMS: what events trigger a lastmod update? Publishing, content modification, template change, plugin update? Disable anything that isn't a genuine editorial modification.

What mistakes should you absolutely avoid with your sitemaps?

• Not segmenting your sitemaps (a single file of 50,000 URLs)
• Including URLs blocked by robots.txt
• Generating automatic lastmod updates with every site build
• Forgetting to submit your sitemaps in Bing Webmaster Tools if you're targeting that search engine
• Putting noindex URLs in the sitemap (an inconsistency Google hates)
• Never checking for sitemap errors in Search Console