Which one of the following is not considered as relevant voucher while vouching cash sales?

The incorrect option is Sales Book.

Key PointsVouching:

• Vouching is defined as the verification of entries in the books of account by examination of documentary evidence or vouchers, such as invoices, debit and credit notes, statements, receipts, etc.
• All such types of documentary evidence are known as vouchers.

Important Points Vouching of Cash Sales:

• Copy of cash memo: Copy of cash memo given at the time of sales to the customer as a proof of payment. This is needed for Vouching of Cash sales.
• Abstract of salesman: This is the record maintained by the salesman for the sales done by him or by the firm. This is also needed for vouching of Cash sales.
• Cashier's summaries: This represents all the cash entries by the cashier of the firm. It will represent an inflow of cash in case of cash sales. So this is also a proof for vouching cash sales.
• Sales book:  Sales book is a type of subsidiary book maintained by the firm recording all the sales done on credit basis. This book does not record the cash sales transaction and hence this will not prove helpful in vouching of cash sales.