Dr. Monzer Kahf, a prominent economist and counselor states: Calculating the amount of Zakah is as simple as adding the Zakatable items in each category of rates (those that are subject to 2.5%, or 5% or 10% or 20% together and multiply by the rate. This exercise must be done every lunar year (354 days), the first such year begins on the day one acquired Nisab for the first time. Please take a look at the booklet “Calculation of Zakah inNorth America” on my Website www.kahf.net or on ISNA website www.isna.net. There is a short form of about 1/2 page and there is a long form and use whichever is suitable.”