Registration of Marriage in the Population Information System
If you are a Finnish citizen and you get married abroad, you must notify the marriage to the Finnish Population System.
Ask the person conducting the marriage, what documents are needed when the ceremony is performed before a foreign public authority. A Finnish certificate of no impediment can be ordered in multiple languages from the Digital and Population Data Agency in your municipality of residence. Documents that are used abroad, must be legalised.
Some clergy members working among expatriate Finns, who are employed by Evangelical Lutheran Church of Finland (list in Finnish), have the right to conduct marriages abroad, but not the right to perform marriage ceremonies abroad.
You cannot get married at an embassy of Finland.
Notify the marriage to the Digital and Population Data Agency
When a Finnish citizen gets married outside Finland it must be notified to the Local Register Office. You can also leave the notification at a Finnish embassy or send it there to be posted to the Digital and Population Data Agency.
The original marriage certificate or a copy of it, authenticated at the mission of Finland, must be appended to the notification. The document must be legalised and if it has been issued in some other language than Finnish, Swedish or English, an authorised translation in one of these languages must be provided. Translations made abroad must be legalised. Translations made by an authorised translator in Finland are valid as such.
An apostille is not required for a marriage certificate issued by the authorities of an EU country. A translation of the certificate is not required, either when the document is accompanied by a multilingual standard form in accordance with the EU Regulation.
Marriage in Thailand
Each country has its own requirements as to what documents are required for concluding a marriage in that country. The examination of impediments to marriage will be carried out in the country where you are to be married. Ask from the local competent authority (District office in Thailand), what documents are needed when registering the marriage with a foreign public authority.
In general, you and your spouse must prove that neither have a valid marriage (Common law system). You can request a certificate that certifies the Finnish legislation gives you the right to enter into the marriage in a foreign country from Digital and Population Data Service Agency https://dvv.fi/en/a-certificate-of-the-right-granted-by-the-finnish-legislation-to-enter-a-marriage-in-a-foreign-country or from your own church in Finland.
The certificate of the right granted by the Finnish legislation to enter a marriage in a foreign country must be in English, signed and original. The certificate is valid for four months starting from the date of issuance. As Thailand is not a member of the Hague Apostille Convention, certificates that are used in Thailand must be legalized first at the Ministry for Foreign Affairs of Finland and then at the Royal Thai Embassy in Helsinki. Kindly note that the Embassy of Finland in Bangkok is not the competent authority by law to legalize documents issued by the Finnish authorities.
If the local authority requires Thai translation of the document, please contact Ministry of Foreign Affairs of Thailand for further proceeding. In addition to the legalized Finnish certificate, please always consult with the local competent authorities to check what other documents are needed for the registration of marriage in Thailand.
Kindly note that a Finnish national is obliged by law to inform Finnish Digital and Population Data Services Agency of one’s marriage being concluded abroad. In order to do so, the marriage certificate issued by the local Thai authority must be legalized first at the Ministry of Foreign Affairs of Thailand and the Embassy of Finland in Bangkok respectively. For further information, see www.dvv.fi.