Stamp duty is a tax on the documents that transfer property. For a buyer it comes in two parts, and the second one is where the real money is.
Buyer's Stamp Duty
Everyone pays , on the purchase price or the market value, whichever is higher. It is charged in slices, like income tax: the first $180,000 at 1%, the next $180,000 at 2%, and so on up to 6% on anything above $3 million. On a $1.5 million home that works out at $44,600.
Additional Buyer's Stamp Duty
depends on who you are and how many residential properties you already own, here or overseas. A Singapore citizen buying a first home pays nothing. A citizen buying a second pays 20% of the whole price — on that same $1.5 million home, an extra $300,000 on top of the BSD.
Permanent residents pay from their first purchase. Foreigners pay 60% on any residential property, except that nationals of a handful of countries with free trade agreements are charged citizen rates.
A married couple with at least one Singapore citizen can apply for a remission on a second property if they sell their first within six months of buying (for a completed property). You pay the ABSD first and claim it back, so you still need the cash up front. Conditions are strict — check with IRAS or your lawyer before relying on it.
Mortgage duty
Small but real: 0.4% of the loan amount, capped at $500.
When it is due
Within 14 days of signing the document in Singapore, or 30 days if it was signed abroad. In practice your conveyancing lawyer files and pays it out of the money you place with them.