System > Configuration > Payment Methods > Zero Subtotal Checkout
Selling products normally consists of you exchanging goods for money. Although there is no doubt that this is how commerce works, there are sometimes cases where you don’t necessarily require an initial transaction at checkout.
Magento Go allows you to sell products (and lets the customers checkout these products) without requiring a payment transaction. This is done using the Zero Subtotal Checkout payment method.
To give you a better idea of when you would use this payment method, let’s use some examples.
Example 1: One example is if you were selling a product or service that would have to be personalized for each unique order. It would be insufficient to give the customer a quote without analyzing the order. In this case, the purchase order (without any transfer of payment) can be used as a starting point for this sale.
Example 2: Another case is if you were selling business-to-business solutions. Similar to personalized products, there would be no initial transactions at checkout. The checkout process would be regarded as a Purchase Order that would later become an invoice.
Example 3: The customer uses a coupon or gift card that discounts the order and shipping total.
Note: You can define which countries are listed in the default list by modifying the Allowed Countries field located in System > Configuration > General > Countries Options.
Tip: Be sure to test this payment method in your Magento Go store before going live.