What is the ruling on zakat for a debt that has not been demanded due to shyness, and the debtor's condition is unknown?

The basic principle is that Zakat (definition) is obligatory on money if it reaches the nisab (definition) and a full year (hawl) has passed on it. A loan does not negate Zakat. If the debt is due and collectable, there are differing opinions regarding it: The Hanafi and Hanbali schools hold that Zakat is not obligatory on it except when it is collected, for all past years. Whereas the Shafi’is believe that its Zakat must be paid every year, just like money in hand. If the debt is owed by an insolvent person or a procrastinator, the prevalent opinion with us is that it is zakatable upon collection for all past years. As for a deferred debt, it is like a debt owed by an insolvent person; it is zakatable upon collection for all previous years.