In a condominium, the operation of the co-ownership is highly regulated, notably by section 18 of the "Condominium act", which stipulates that the co-owners must jointly pay the expenses related to the operation and maintenance of the building's common areas in proportion to the surface area they own.  The Maintenance Fees are these expenses, which are expressed as an amount per sqm. This amount varies according to the age and the different equipments of the building, between 25 and 60 THB/sqm.  To help you, you can take as an order of magnitude the value 1€/sqm, or, for example, 75€/month for a modern 3-room apartment of 75 sqm.  For housing estates, the regulations are a little less strict, but the operation is basically the same. However, the calculation is not always exactly proportional to the number of sqm of land. The amount of the charges can be calculated with a combination of the built area and the garden area, or sometimes it can be determined by the type of villa.  What these charges include can vary from one development to another. Some separate the common areas from the private gardens, leaving each owner free to maintain their own garden and swimming pool. While others include this maintenance in the charges to ensure that each garden and/or pool is maintained to the same standards.