If you purchase a second house, you’ll first have to pay the ABSD as usual (this is within 14 days of the date of purchase). However, you can apply for a remission if you sell your first home within six months of buying the second one.
If the second property is under development (e.g., a new launch condo), you must sell your first house within six months of the second property getting its Temporary Occupation Permit (TOP) or Certificate of Statutory Completion (CSC), whichever is earlier.
Whether it is worth it depends on your personal financial situation and long-term goals. It is advisable to consult with a financial advisor to make an informed decision.
Best of luck with your property decisions!