How is zakat calculated for this money, which has been owned since March 2013, with the desire to pay it in the coming Ramadan? Is zakat due this year or next year, and how would the calculation be if it is paid after a year and four months?

Scholars have differed on the effect of debt on the obligation of Zakat (definition). The majority opinion is that debt prevents the obligation of Zakat on hidden wealth. The Maliki school, however, provides a detailed view on this matter. As for debts owed to you by others, Zakat becomes obligatory on you for them every year, and you have the option of either paying it annually or delaying it until you collect the debt.

Regarding paying Zakat in Ramadan (definition): paying Zakat before its due date (the completion of the hawl or lunar year) is permissible, while delaying it beyond its due date is prohibited. Therefore, it is permissible to pay the Zakat for the current year in the Ramadan preceding its due date, but it is not permissible to delay it until the Ramadan following its due date. It is permissible to pay Zakat in advance before it becomes due, once the reason for its obligation exists, according to the majority of scholars. The hawl for trade goods is based on the hawl of the currency with which they were purchased.