Assalam o Alaikum,
I have a question regarding Zakah calculation from my salary accounts. I receive monthly salary directly to my bank account from which I do my expenditures. Since I started working, my bank balance has kept growing from that of previous year and never went below Allhamdulilah. By now I have 3 accounts with balance with rough estimations:
Bank Account 1: ~9000$ (Static from a long time)
Bank Account 2: ~24000$ (Active till December 2019)
Bank Account 3: ~5000$ (Active from January 2020)
The method I used till last year was, I would check the balance of previous year, and based on that I would pay Zakah. But I had confusion on the salary that I received a month later after the calculation date of last year. By the current year it would be a month short from a full year according to my calculation and I didn't include it. And by next year it would be almost 2 years passed to pay Zakah on that amount.
Then I watched/read many lectures where most scholars suggested that it is easy to pay Zakah on the lump sum amount that you have by the time of paying Zakah. Which arises another question, if I received a salary last month, I would include that in current Zakah calculation and by next year I would pay double Zakah on it.
Also, for previous year, I had only Account 1 and 2. Account 1 calculation came out correct because the amount didn't change, but for Account 2 I paid partial amount from the wrong calculation and got confused, and that Zakah is also pending.
Please guide me on how should I calculate my Zakah for current year, what should I do for last year pending Zakah, and for all previous years where I might and could have had wrong calculations? I have been paying Zakah for about 3 years now.