If I had extended the tenancy period, do I need to stamp on the extension? And how is the stamp duty computed?
If there is a new lease extension contract, or if a variation to the Tenancy Agreement was executed due to an increase in rent or the extension of the lease period, stamp duty is payable on the document based on the increased rent or the rental for the extended lease period. The lease duty rate is 0.4%.
You can stamp the document at myTaxPortal, click on "Stamp Duty" and under "Stamping" > "Lease/Tenancy" > select "Variation of Lease" under the Nature of Transaction.