If the property was primarily purchased to live in or rent out for fixed income, then Zakāh will not be due. However, if it was purchased as an investment with the intention to gain from the appreciation, then Zakāh is due every year on the current market value.
If you purchased it to sell but then decided to live in it, you will not pay Zakah. If you purchased it as a rental then decided to sell, it will not be Zakatable even if it is listed for sale.
You might have a dual intention to both rent it out and then sell it once the value has increased. It is difficult to give a clear answer in this scenario whether Zakah is due or not. One possible question to ask yourself is: if you could not collect any rent at all would you still have bought this property? Let’s assume you intended to rent out the property for ten years hoping for a 6% annual return and a 3% annual value increase. If you would have purchased the property without factoring in the 6% annual rental income then it means you primarily purchased it for captital gain, and must pay Zakah yearly. If you would not have, and invested your money elsewhere hoping for a higher return, then your primary intention was not for capital gain so you do not pay Zakah.
Shaykh Mustafa Umar