Is Zakat obligatory on a sum of 13,000 Omani Riyals saved for building a house, considering withdrawals have been made from it over two years, and what is the amount of Zakat due?

Zakat (definition) becomes obligatory on wealth when it reaches the nisab (definition) (threshold) and a full hawl (lunar year) has passed over it. The hawl for accumulated, saved wealth begins from the day it reaches the nisab either by itself or by being added to other money or trade goods owned by the person. The nisab for banknotes is equivalent to 85 grams of gold, and the amount of Zakat due is 2.5% (a quarter of a tenth). If the new money is a profit from the initial wealth, then its Zakat is due with it and its hawl is its hawl. However, if it is not a profit from it, then Zakat is not obligatory on it until a full hawl passes over it. It can be added to the initial wealth, and Zakat for all of it can be paid when the hawl of the initial wealth is completed, or one can wait for its hawl to be completed, calculated from the date of its acquisition. It is not a condition for the new money to reach the nisab on its own because it follows the initial wealth in terms of nisab. If years have passed and Zakat has not been paid on wealth that has completed its hawl and reached the nisab, then Zakat must be paid for all past years. Zakat is not waived just because the money is intended for building a house, as long as the money remains until the completion of the hawl.