To facilitate investment, on November 23, 2009, the Board of Investment will open the One Start One Stop Investment Center (OSOS) at Chamchuri Square in Bangkok’s Central Business District (CBD).
The establishment of the OSOS is a direct result of the government’s efforts to work with investors to solve problems that are important to the investment community. When the government of Prime Minister Abhisit Vejjajiva took office in January of 2009, one of the urgent tasks it set was to enhance investor confidence.
To accomplish this, his administration has made it a priority to address issues concerning investors. One of those issues raised in a series of consultative meetings was the need to better facilitate investors as they had to deal with multiple agencies spread all across Bangkok. To respond to their needs, the government tasked the Board of Investment with creating the OSOS.
The primary objective of the center is to facilitate the entry of new investors and assist those already with investments in Thailand who wish to expand. For businessmen — Thai or foreign; big or small; BOI-promoted or not — interested in investing in Thailand, the One Start One Stop Investment Center will offer investors a wide range of investment-related services.

When it opens, the center will house representatives of key investment-related agencies — more than a dozen in total — including the Board of Investment, several other agencies under the Ministry of Industry, Department of Business Development (Ministry of Commerce), Industrial Estate Authority of Thailand, the Revenue Department (Ministry of Finance), Department of Export Promotion (Ministry of Commerce), etc.
OSOS staff will help investors with various applications to make sure they understand what is needed to register a company, obtain investment promotion privileges, obtain a foreign business license, complete an environmental impact assessment, request permission to use land for industrial operations, obtain utilities, etc.
OSOS staff will also accept applications for things such ascorporate name registration,corporate tax ID numbers, VAT registration, foreign business licenses, investment promotion incentives, etc.
More here BOI.