A book debt is a sum of money due to a business in the ordinary course of its business. It has been described as a debt that would normally be entered in the books of the business regardless of whether or not it is in fact entered.
Book debts include sums owed to a business for goods (www.practicallaw.com/A36216) or services supplied or work carried out. Sums due under loans may also be treated as book debts.