Collectible debts
In one sentenceDebts owed to you by people who can pay, acknowledge the debt and do not delay, and that are expected to be collected on demand, so for Zakat they are treated like wealth you hold.
Simply put
The test is not whether the debt is in the books, but the debtor's situation: is he solvent, does he acknowledge the debt, and does he pay when asked?
If you doubt that a particular debt will be collected, separate it from the collectible debts and do not add it to your zakatable wealth until its situation is clear or you receive it.
Example
A fabric shop owner reviews his debts on the Hawl day: a debt owed by a business that pays regularly is added to his Zakat, and a debt owed by a customer who closed his shop and disappeared waits until it is received.
Don't confuse it with
ProvisionsThe allowance for doubtful debts is an accounting estimate in the statements, while classing a debt as collectible or doubtful is a Zakat ruling on the debtor's situation.