Catalog set up
Add a deposit as an option to your product to include a deposit amount in the order (e.g "Beer Glass Deposit, +1€").
Create a product with a negative price that matches the deposit amount (e.g "Beer Glass Deposit Refund, -1€").
Ordering session
Open a new order.
Add the option (deposit) to the product (e.g "Beer Glass Deposit, +1€) and then close the order.
When your customer returns the item, open a new order.
Select the product with the negative price (e.g "Beer Glass Deposit Refund, -1€").
Close the order.
For accurate accounting, ensure the tax rate matches the item from which the deposit refund originates. You can also track the deposits charged (if used as an option) and refunded from your Product Sales Report by viewing those by the product name you created in your catalog (e.g. “Beer Glass Deposit”).