Money owed that has not been paid to you after a period of time is commonly known as a bad debt.
Money you can't collect. Businesses are allowed to deduct bad debts under certain circumstances. If a bad debt is personal, it may be deducted in some cases as a short-term capital loss. Loans between family members generally are classified as non-business.
If a customer of a business fails to pay the bill for goods or services received, the unpaid amount is a "bad debt". Although the sale is included in the declared turnover, the bad debt is an allowable expense. Where tenants fail to pay rent due, the bad debts are allowable rental expenses.