Should You Sell Your HDB Before MOP or After MOP? So you have finally decided to sell your HDB flat and purchase a private property, either to upgrade your current home or just because you want to move out of Singapore and explore other places? If so, you might be wondering when the best time to do it would be. You can always consult your financial planner, an experienced property consultant, or real estate agents like MOP upgraders about this matter. You can also take it upon yourself to do some research on the matter by asking yourself two questions: Should I sell my HDB before or after the MOP? And what does MOP mean anyway?