All taxes are to be paid locally according to the local law. Transfer tax rate for the estate transactions (Stamp Duty Land Tax) is 4% (with “seasonal discionts” as currently 3% ) . That is calculated on the base of your declared price. What price shall you declare than? According the law the real sale price what of course in practice hardly ever does anyone. The cadastro offise will ask you for the official govermental value document which manucipality gives and which usually is ca. 40-60% lower than the actual market value, plus the expertise report which for you will need to pay ca. 1500-1700 TRY. the expertise report is for showing the market value, what in practice as I see since 4th of March 2019 is not always the exact market value. Anyhow the same rules works you can not declare less then the govermental documents sais. But also you are not forced to declare what the expertise sais as the owner of the property you are the only one who can decide for how much you are selling. Nobody can forbid you to sell cheapper than expertise sais, if this is what you want/need to do… The Buyer shall pay that tax half-half with the Seller, but in practice the Buyer covers this cost.