Who can register a .co.th domain, and why choose one?
A .co.th domain can only be registered by a business that proves it exists: typically a company registered in Thailand, or a foreign company with a Thai trademark or other documented link to the country, under the rules set by THNIC, the registry for .th.
That paperwork is the point. Thai buyers read .co.th as "a real company here", which is why banks, law firms, clinics and B2B suppliers often prefer it to a .com that anyone can buy in two minutes.
The trade-off is effort. Registration takes documents and an approval step, and the name you can have is tied to your company name or trademark. This guide assumes you have already decided on .co.th; if you are still weighing extensions, read our piece on choosing a domain name first.
Rules change, so treat everything below as a map and confirm the details on THNIC's website before you submit.
Who can register a .co.th domain?
Eligibility turns on the business, not the person filling in the form. The groups below reflect THNIC's published categories at the time of writing; check the current list before you apply, because the registry has widened and adjusted the rules over the years.
- Thai-registered companiesLimited companies and partnerships registered with the Department of Business Development. This is the most common and simplest case.
- Foreign companies operating in ThailandBranches or representative offices with a Thai registration or licence document.
- Foreign companies with a Thai trademarkA trademark registered with the Thai Department of Intellectual Property can support the application.
- Other registered businessesTHNIC's policy also lists documents such as a VAT registration certificate (ภ.พ.20) or a commercial registration; confirm the accepted document type with THNIC first.
What does not qualify: a private individual, a freelancer without a registered business, or a project that has no company or trademark behind it yet. Those cases usually fit .in.th or a generic extension better.
What documents does THNIC ask for?
The document proves the right to the name. Which one you send depends on the route you use:
- Company affidavit (หนังสือรับรองบริษัท) issued by the Department of Business Development. Use a recent copy; registrars often reject old ones.
- Thai trademark registration certificate from the Department of Intellectual Property, for companies registering under a brand.
- Foreign registration or licence documents, for branches and representative offices, sometimes with a translation.
Prepare clear scans or PDFs, make sure the company name matches the one in the domain request exactly, and have an authorised person's details ready as the registrant contact. Missing or unreadable documents are the main reason applications stall.
How the name must relate to your company
Unlike .com, a .co.th name cannot be anything you like. It has to relate to the company name or trademark in the documents. In practice registrars accept the full name, a recognisable abbreviation, or the registered trademark. As hypothetical examples, a company registered as "Siam Riverside Hospitality Co., Ltd." could reasonably apply for siamriverside.co.th or srh.co.th, while riversidehotelbangkok.co.th would need a supporting trademark or other justification.
Points that trip people up
- Thai company names: if the affidavit shows only the Thai name, the romanised spelling in the domain should be a reasonable transliteration. Registrars may ask you to explain it.
- Generic words: a descriptive word such as "hotel" or "dental" on its own is usually not accepted unless it is the registered name or mark.
- Product brands: register the trademark first if the site is for a product rather than the company.
If the name you want is rejected, you can register the closest acceptable .co.th and use a generic domain for the marketing name, with one redirecting to the other.
The registration process
You can register directly with THNIC or through an accredited registrar, and many hosting companies act as resellers. Prices and renewal fees differ by provider, so compare them on each registrar's own pricing page rather than trusting a figure in a blog post. The steps look like this:
- Step 1
Check availability
Search the name on THNIC's WHOIS or your registrar's search.
- Step 2
Choose a registrar
Pick THNIC or an accredited registrar; check renewal prices, support language and how easy it is to change DNS.
- Step 3
Submit the request and documents
Enter the registrant as the company, upload the affidavit or trademark document and pay.
- Step 4
Wait for review
The registry or registrar checks the documents and may ask for corrections.
- Step 5
Point the domain
Once approved, set DNS for the website and email, and record the login details somewhere the company controls.
Renewals, ownership and contact details
The most expensive domain mistake is not a fee. It is finding out, years later, that the domain was registered in the name of a former employee, a web agency or a relative, and that the registrant email bounces. For a .co.th this is especially painful, because proving the company's right to the name again takes paperwork.
Keep these in the company's hands
- Registrant: the company itself, never the developer. Insist on this with any developer or agency, including us.
- Account login and contact email: a role address such as it@ or admin@ on your own domain, not a personal Gmail.
- Renewal: multi-year terms reduce the risk of a missed renewal. Turn on auto-renew and keep a valid payment method on file.
If the domain sits with the wrong registrar or the wrong person, our domain transfer guide covers moving it. Once the domain is live, set up business email on your own domain so staff stop using free addresses, and make sure a WordPress backup of the site lives somewhere you control too.
Using .co.th and .com together
Many Thai companies hold both, for example a .co.th for local trust and a .com that matches the brand abroad. That is fine, as long as only one of them serves the website. Pick a primary address, then send the other to it with a permanent 301 redirect that keeps the path, so yourname.com/contact/ lands on yourname.co.th/contact/.
Which one should be primary? If most customers are Thai and the brand is local, .co.th is the natural choice. If you sell mainly to overseas buyers or tourists, a .com may read more familiar to them. Running two copies of the same site on both addresses splits search signals and confuses analytics, so avoid it. Email can still work on both domains if you set it up for each, with the SPF and DKIM records that keep your mail out of spam folders.
Where the site is hosted is a separate decision, and server location has little direct effect on SEO; our overview of shared, cloud or managed hosting explains the options.
Other .th domains
.co.th is one of several second-level .th domains, each for a different kind of organisation:
- .in.th: open to individuals and organisations without company registration. A good fit for a freelancer or a new project.
- .or.th: registered non-profit organisations and foundations.
- .ac.th: academic institutions.
- .go.th: government agencies.
Once the domain is sorted, the website is the next step. Our website development service covers bilingual Thai and English sites built on WordPress, Shopify or WooCommerce, and we can point your .co.th at the new site at launch. For the upkeep afterwards, including domain and certificate renewals, see what care after launch costs.
More guides on domains and hosting
Sources
- THNIC: .th domain registration requirements
- THNIC: registration policy and accepted documents
- Department of Business Development: company affidavit
- Department of Intellectual Property: trademark registration
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