Is it permissible to pay zakat in monthly installments to support certain families, and is it obligatory to make up for nine years of delayed zakat due to ignorance of its obligation?

There are two scenarios for paying zakat in installments: paying it in installments before it becomes due (advancing zakat), which is permissible; and paying it in installments after it becomes due, which is not permissible except for a compelling benefit or an excuse. As for the past years, you must pay their zakat immediately, as it is a debt owed to the poor, and delaying it is considered a forbidden procrastination.