What is the method for calculating Zakat on wealth that has reached the nisab, when the date of reaching the nisab has been forgotten? And is Zakat obligatory on money saved for a mother to perform the Hajj obligation? And is it permissible to disburse Zakat in the current country of residence which has a Muslim minority?

If the wealth reaches the nisab (definition) (minimum threshold) and a hawl (lunar year) passes over it without decreasing below the nisab, zakat (definition) becomes immediately obligatory on it, and repentance is necessary if its payment is delayed. Whoever doubts whether their wealth has reached the nisab does not owe zakat. Reaching the nisab can be determined by bank statements and gold prices, or by considering the month in which one is certain that the nisab has been reached. The money given to the mother is counted as part of your zakat-liable wealth for the period it was in your possession, and its zakat is obligatory. After it is given to the mother, its zakat is no longer obligatory on you, but becomes obligatory on her if a year passes while it is in her possession. The general rule is to disburse zakat in the country where the wealth is located, but it is permissible to transfer it for a compelling reason.