National Housing Authority, a state enterprise under Ministry of Social Development and Human Security, was established on February 12, 1973 in compliance with the National Executive Decree No. 316. It currently operates under the National Housing Authority Act, B.E. 2537 and the National Housing Authority Act, B.E. 2550 (the amendment Act). NHA was created by merging related government agencies that provided affordable public housing for the country: Housing Welfare Division under Department of Social Welfare, Office of Housing Welfare, Housing Welfare section of Government Housing Bank, and Office of Slum Improvement under Bangkok Metropolitan Administration (a local governmental unit).