The sinking fund is a common fund paid by owners of all NEW condo or villa properties. It is a fund reserved for repairs, repainting, structural fixes, equipment replacement of common areas and facilities. Normally a sinking fund is calculated on the price per square meter multiplied by the living area of your owned property. It is paid once, up-front, although in rare cases it will need to be replenished after a number of years, upon agreement of all involved parties (developer and all owners).
This is a totally separate fee to the maintenance fees. It is only payable on new residential properties and is not required on any existing or completed properties.
The juristic department should be transparent in providing evidence of allocation of sinking funds and it is common for owners with voting rights in a project to collectively vote to determine where funds should be spent.