An insertion voucher is a document or coupon that is used to add an item or service to an existing transaction or agreement. It serves as proof of the addition and typically includes details such as the date, description, and cost of the inserted item. This type of voucher is commonly used in business transactions, particularly in the advertising industry, where it is used to add new advertisements to a pre-existing contract. Insertion vouchers provide a convenient and organized way to keep track of additional items or services added to a transaction, ensuring accuracy and transparency for all parties involved.