Sales return day book is written up from the copies of the credit notes sent to customers. At the end of the month, the total of the sales return book is debited to the sales return account in the nominal ledger. Credit is made in the personal account of the customer in the trade receivable ledger.
In other words, sales return day book record the items which have been returned by customers hence this lead to a reduction of sales amount and account receivables as well. So the entity accumulates all return for certain period for example week or month and after that, they add them up, and then they debit sales return account and credit personal account of the customer in the trade receivable ledger.
Customers can return the purchased items for various reasons such as the item being defective, items lacking required specification and so forth