in the example tht i gave, from month 3 to month 17 (assume them Islamic months) there has been 6000$ in the account, out of which zakat has been paid on only 1000$ (in month 0) and the rest 5000$ had completed one year unused with the person in the month 15 which was never accounted for…
instead when he spends 4000$ in month 17, when the money had been with him for well over a year, he is left with 2000 off which he pays zakat in month 24…
THAT IS WRONG…
now had he followed the method of paying off zakat on all the balance he had in his account every year, he wud have paid off the zakat on 6000$ in month 12, instead of only on 1000$…
then when he went to month 24 with only 2000$, he need not worry about the 5000$ that spent 14 months in his account untouched, cuz he has already paid off the zakat in advance…