Foreign investors who wish to invest and carry out business in Thailand must first consider the provision of "Foreign Business Act 1999” (FBA 1999).

For more details, please visit:https://www.dbd.go.th/dbdweb_en/ewt_dl_link.php?nid=4047

In simple terms, "foreigners” under the FBA 1999 including foreign individuals, foreign registered companies (such as representative office, branch office), companies registered in Thailand but majority shareholder owned by foreigners and partnerships managed by foreigners.

According to FBA 1999, the interior design consulting is under List 3 (21) "Other service business, except service businesses prescribed in ministerial regulations". Foreign investor who intends to engage in such business could apply to get foreign business license from the Director - General of the Department of Business Development, Ministry of Commerce, by and with the approval of the Foreign Business Committee. In addition, the minimum capital requirement for business under this Act must not be less than three million baht.

Law and rules of foreign business license (If your business activity is in a list of foreign business act, your company may need to apply for foreign business license) please see the information from this link:https://www.dbd.go.th/dbdweb_en/download/article/article_20131219100443.pdf