The message was a single line: a power of attorney for a patent registration process, one signer, Thailand as the destination. The client also ticked the doorstep option, so a notary would come to them rather than the other way round. That sounds like one short appointment. In practice, a power of attorney for a Thai patent filing has two readers who do not share an office (a Thai patent agent and the Thai Department of Intellectual Property), and the right notarial step depends on what the first of them asks for. Getting that answer before the notary visits was most of the job.
| Item | Detail |
|---|---|
| Enquiry received | 3 November 2026 |
| Service requested | Notarial certificate |
| Document | Power of attorney for a patent registration process |
| Where it will be used | Thailand, before the Department of Intellectual Property (DIP), through a Thai patent agent |
| Signers | One |
| Add-on | Mobile notary visit within Singapore |
| Document uploaded | None at the time of enquiry |
| Translation | Not requested; English stated as the document language |
| Status | Scoped and advised; order not confirmed at the time of writing |
A patent filing that starts with a signature in Singapore
The client came to us through our mobile notary page after a Google search, and that tells you a little about where they were in the process. People who search for a notary who will come to them have usually already been handed a document by somebody else and told to “get it notarised”. In patent work that somebody is almost always a patent agent in the filing country, who needs written authority before they can act for the applicant at the patent office.
Thailand works this way. The Thai government’s guide to applying for an invention patent says that applicants who do not live in Thailand must appoint a patent agent or patent attorney registered there to act for them. Without that authority the agent cannot file or respond to the office, so a delay on the power of attorney can become a delay on the patent itself.
The client had not uploaded the document and had not said whether they were signing as an individual inventor or for a company that owns the invention. They had told us the two facts that mattered most: one signer, signing in Singapore for use in Thailand.
Three levels of certification, and only one of them is ours to choose
Here is the part that makes a Thai patent power of attorney less simple than it looks. The guidance we read on the Thai government’s guide-book page lists several people who may certify the signature on a power of attorney made outside Thailand. It names an authorised official of a Thai embassy or consulate, the director of a Thai Ministry of Commerce office in the country where the grantor lives, a person authorised to certify signatures under that country’s law, and a notary public. The DIP’s own checklist for international (PCT) patent filings likewise asks for a power of attorney “with notary stamp”.
Read literally, that suggests a notarised signature could be enough. In real files, a Thai agent may still ask for more, because they are the ones who will face the office if something about the document is questioned. So the request could land at any of three levels:
- Notarisation only: the notary witnesses the signature and issues a notarial certificate.
- Notarisation plus authentication by the Singapore Academy of Law (SAL).
- Notarisation, SAL authentication, and then legalisation by the Royal Thai Embassy in Singapore.
We did not pick a level for the client. Our first piece of advice was to ask the Thai agent, in writing, which of the three they wanted, and to forward the answer before the visit was booked. A notary can do the first step perfectly and still leave the client a step short if nobody asked the question.
The apostille question that is bound to come up
Anyone researching this will soon read that Thailand has joined the Apostille Convention. That is true, but not yet in force. The HCCH, which administers the Convention, records that Thailand deposited its instrument of accession on 30 June 2026 and that the Convention enters into force for Thailand on 28 February 2027. On the date of this enquiry, an apostille on its own was not the route into Thailand.
That matters for the third level above. SAL’s published FAQ says that once a document has been notarised, the notarial certificate must be authenticated by SAL, and that SAL affixes an apostille to every document it authenticates. The same FAQ says documents bound for countries outside the Convention still need further legalisation through the relevant foreign mission in Singapore. For Thailand, before 28 February 2027, that mission is the Royal Thai Embassy.
The embassy’s page on verifying non-Thai documents is consistent with this. It says documents must be legalised by SAL and that applicants bring an original and a copy bearing the seal of a Singapore notary public. It also says documents must be in English, or come with an English translation. The page sets out its own counter hours, fee and processing time. We pointed the client to it rather than quoting those details, because they are the embassy’s to change.
If the client’s timetable slipped past 28 February 2027, it would be worth asking the agent again, because the route may change.
What the doorstep appointment would actually involve
A mobile visit changes where the notary sits, not what the notary does. The steps are the same as in an office, and they are worth spelling out because they explain why some common shortcuts do not work.
- Identity first. The signer shows original photo identification, normally a passport or NRIC, and the name on it should match the name on the power of attorney. A mismatch, such as a missing middle name or a different order of names, is better raised with the Thai agent before the visit than discovered at the table.
- Signing in the notary’s presence. The notary certifies that the signer signed in front of them. A power of attorney that arrives already signed cannot be certified that way, so the signature lines should stay blank until the notary is there.
- Capacity, if a company is involved. If the client signs as a director or officer of a company that owns the invention, we would ask for something showing their authority to sign for it. The Thai agent may have their own list of company documents too.
- The notarial certificate. The notary attaches or endorses a certificate recording what was witnessed, then signs and seals it. That certificate is what SAL later authenticates, if the agent asks for that level.
Our doorstep notary service in Singapore covers exactly this appointment. It suits single-signer documents like this one well.
Book a notary to come to you →
Why the wording stays with the Thai agent
Clients sometimes ask the notary to “fix” a power of attorney while they are there. For a patent filing we would not do that. The Thai agent prepares the document, usually on a form they know the office accepts, with the powers they need: filing, amending, responding to office actions, perhaps paying fees. If the scope is too narrow, the agent finds out when they try to act. If we rewrite the scope in Singapore, we may create a document the agent did not ask for and cannot rely on.
The notary’s role here is narrower and firmer: confirm who signed, confirm they signed in person, and certify that. Our power of attorney notarisation work follows the same rule for every destination. The receiving party owns the content, and the notary certifies the signing.
Is a Thai translation part of this?
The client said the document was in English and did not ask for a translation, and nothing in the enquiry suggested otherwise. On the Singapore side that is straightforward. The embassy’s own page asks for documents in English.
The Thai side is less clear-cut, and we said so. The patent application itself is filed in Thai; the DIP’s PCT checklist, for example, asks for the request form and invention details in Thai. We did not find DIP guidance saying whether an English power of attorney must also be translated into Thai. That is a question for the Thai agent, who will know what they will file alongside it. If they want a Thai version, it is usually far simpler to settle that before the signing than to add it after legalisation.
Where the enquiry rests
On our side, the enquiry has been scoped and the advice given. We confirmed that a notarial certificate for one signer at a doorstep appointment was the right service. We set out the three possible certification levels and asked the client to get the Thai agent’s choice in writing. We flagged the Apostille Convention date and asked to see the power of attorney before booking. At the time of writing the order had not been confirmed, and we have no information about the patent application itself, which is a matter for the Thai agent and the DIP.
The approach is close to the one in our Hong Kong bank account signatures case study, where the bank’s own pack had to be seen before the certificate could be settled.
Lessons for anyone signing a Thai patent power of attorney
- Ask the Thai patent agent which level they need: notarised, notarised and SAL-authenticated, or fully legalised by the Royal Thai Embassy.
- Thailand’s accession to the Apostille Convention takes effect on 28 February 2027, so until then an apostille alone is not the route.
- Do not sign before the notary arrives, whether the appointment is at home, at work or in an office.
- Bring original photo ID with a name that matches the document exactly.
- Leave the wording to the Thai agent and ask them about any Thai translation before the signing.
Questions about notarising a power of attorney for a Thai patent
Is notarisation in Singapore enough for the Thai Department of Intellectual Property?
The Thai guidance we read lists a notary public among the people who may certify a signature on a power of attorney made abroad. Your Thai agent may still ask for SAL authentication and Royal Thai Embassy legalisation on top. Ask them before you book.
Thailand has joined the Apostille Convention. Can I just get an apostille?
Not yet. The HCCH records that the Convention enters into force for Thailand on 28 February 2027. Before that date, documents for Thailand still go through embassy legalisation after SAL, if the receiving party asks for legalisation.
Can a mobile notary handle a patent power of attorney at my home or office?
Yes. The appointment is the same as in an office: identity check, signing in the notary’s presence, then the notarial certificate. Only the location changes.
The Thai agent emailed me the document. Can I sign it now and send it to the notary?
Please do not. The notary certifies a signature made in front of them, so leave the signature blank until the appointment.
Can the notary add powers the Thai agent forgot?
We would not change the wording of a patent power of attorney. If you think the powers are too narrow, ask the agent to send a revised version before the visit.
I am signing for a company, not as the inventor. Does anything change?
You still sign in person with your own ID. We would also ask for something showing that you have authority to sign for the company, and the Thai agent may want company documents of their own.
Ask us to scope your Thai patent power of attorney →
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Client details in this case study have been withheld or changed to protect privacy.
Based on a real request our team handled. The document, purpose and requirements are described as the client shared them, with all names and personal details removed.