What is the most common hreflang mistake?

Missing return tags. If the English page points to the Thai version, the Thai version must point back, or search engines ignore the pairing entirely. The next most common errors are using the wrong language codes and pointing hreflang at non-canonical URLs.

Do I need hreflang for a Thai and English site?

If both versions target different audiences at different URLs, yes. It tells Google to show Thai speakers the Thai page and English speakers the English one, instead of picking for itself. It also stops the two versions being treated as duplicates competing with each other.

Technical SEO

Hreflang

Hreflang is an HTML attribute that tells search engines which language and region a page targets, so the right version is shown to the right user.

A site with English and Thai versions uses hreflang pairs so Thai searchers get the Thai page and English searchers get the English one. Implemented wrong, it can cause the wrong-language page to rank or pages to compete with each other. Each version should reference all the others, including itself.

For Thai and English sites the usual failure is not the tag syntax but the URL structure it points at. Hreflang must reference canonical, indexable URLs, so pointing it at a URL that redirects or carries a canonical elsewhere makes the whole cluster invalid. Return tags must also be complete in both directions. Use th for Thai rather than th-TH unless you genuinely serve different content by region, since narrower codes reduce which searchers see the page. Search Console no longer reports hreflang errors, so validate with a crawler that renders the tags as they ship.

Example

A hotel's English page ranks in front of Thai users while its Thai page sits unseen, and each language page competes with the other. Adding paired tags, EN pointing to TH, TH pointing back, x-default set, tells Google which audience each serves. Thai searchers start seeing the Thai page, and the two URLs stop cannibalising each other.

Frequently asked questions

What is the most common hreflang mistake?: Missing return tags. If the English page points to the Thai version, the Thai version must point back, or search engines ignore the pairing entirely. The next most common errors are using the wrong language codes and pointing hreflang at non-canonical URLs.
Do I need hreflang for a Thai and English site?: If both versions target different audiences at different URLs, yes. It tells Google to show Thai speakers the Thai page and English speakers the English one, instead of picking for itself. It also stops the two versions being treated as duplicates competing with each other.

Related terms

Canonical Tag Indexing SEO

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