How is Zakat calculated on real estate contributions (musharakah)? Is it only on the amount received, or on the full amount? And what about previous and coming years, especially after the liquidation of the contribution has been delayed for years?

Whoever owns a zakatable amount (nisab) and contributes it as shares in a property designated for sale, must evaluate his shares and pay a quarter of a tenth (2.5%) when a complete year (hawl) passes over the money. If the liquidation is delayed, then either the money is a debt owed to him, in which case there is no zakat due until he receives it, or the partnership is still ongoing, in which case zakat is due on his share every year.