5. Is there any difference between 'residential' and 'commercial' properties as far as stamp duty is concerned?

For residential properties, stamp duty is payable upon the signing of the provisional agreement and/or formal sale and purchase agreement. If a formal agreement is signed within 14 days from the date of the provisional agreement, only the formal agreement has to be stamped.

For commercial or non-residential properties, stamp duty is payable only when an "assignment" is signed. An assignment is a document for transferring the title (i.e. property ownership) from the vendor to the purchaser. It will be signed on the completion day, which is the property handover day.