The contribution is fixed in the sale and purchase agreement as an amount in baht per square metre of unit area and is paid at transfer, on top of the price. It belongs to the building, not the owner: nothing is refunded on resale, and a resale buyer does not normally pay it again.

The fund is separate from the recurring common-area fee, which covers day-to-day running costs. It exists so that large, infrequent bills do not fall on owners all at once. When it runs low, the co-owners can vote at a general meeting to top it up, which means a special levy on every unit.

That is the point to check when buying in an older building. Ask the juristic person for the current balance, the audited accounts and any planned works. An ageing building with a small fund and tired lifts, pool plant or facade will need money from its owners soon.

For new developments, compare the rate between projects. See property taxes and buying costs and title deeds and due diligence.