Sheikh Abdur-Rahman Zyka
Assalamu Alaykum Wa Rahmatullahi Wa Barakatuh
All praise and gratitude are due to Allah SWT. May the blessings and peace of Allah SWT be upon His Messenger PBUH. Donations or general Sadaqah does not count as Zakat, as mentioned in many traditional books of Fiqh. One of the main reasons behind this is that a very important condition of Zakat is An-Niyyah, or the intention.
Imam An Nawawi says in his book Al Minhaj, “If someone was to give five dirhams and intended that they are for both the compulsory Zakat, and also a general Sadaqah, it does not count as Zakat and it is just general charity because the intention in Zakat must be only for Zakat”. This is regardless of whether it is charity given on one’s own behalf, or on behalf of another person (e.g. someone who has passed away).As for calculating Zakat al-Maal, there are multiple way people use. One of the easiest ways to calculate Zakat, is to divide the money that Zakat needs to be paid on by 40 and the result (which would amount to 2.5%) is the amount of Zakat or a little bit more.
For example, if Muhammad has had 6000 dollars for an entire Hijri Year and Zakat is due on these $6000, he does the following: 6000 ÷ 40 = 150, So he pays 150 dollars in Zakat. As for which nisaab to use, this is a matter that the scholars differ upon, and it is generally advised to adopt whichever is lower of either silver or gold nisaab. This is in the interests of caution.
If you do not remember when you reached the nisaab threshold, i.e. when your Zakat then becomes payable, then it is best to backdate your Zakat for a year, as if you had reached the nisaab one year ago, even if for part of the year you might not have. This is fine as long as you have reached the nisaab value at present.One is also permitted to pay Zakat in advance if it is not yet due. The opinion of Al-Shafi’i is that once the nisaab is reached, Zakat can be paid before the end of the year, but it cannot be paid before the nisaab has been reached, nor can it be paid more than one year in advance.
The opinion of Imam Ahmad is that Zakat can be paid two years in advance, the opinion of Imam Abu Hanifa is that Zakat can be paid even more than two years in advance, and finally, Imam Malik holds the opinion that Zakat cannot be paid in advance unless it is a very short period in advance.
And Allah knows best.