Zakat - Due for more than 5 years

Assalamu Alaikum

When my dad retired. He got a settlement, and a good part of it was put in as a bank fixed deposit since 2018, No zakat has been calculated it on it so far. I have the following questions,

  1. How do you calculate the Zakat’able amount? It’s above Nisaab. I was thinking of 2.5% of the amount minus the expenses and losses (devastating floods) over the period.
  2. Is there any other measures we need to take for being ignorant and not paying it for this long

@Mufti_Billal @Mufti_Faraz_Adam

Assalamu Alaikkum Shuyukh, It would be great if help if any of you can answer this question.

JazakaAllah Khayran

Wasalam

May Allah bless you.

  1. Just look at the amount he had on his zakat anniversary date and pay 2.5% on the total for each year the zakat was not paid. However, I am not sure if this fixed deposit account was a conventional bank and had compounded interest? If that is the case, then you will exclude the interest amount from the zakat calculation.

  2. No specific measures, beside trying to pay the zakat as soon as possible even if its in instalments.

Kind regards