How does billing work when I sign up for new hosting using a promo code?

In general, promo codes are applicable with the establishment of new hosting for a domain. 

When an order form is processed containing a valid promo code, a first payment using credit billing information will need to be successfully processed in order to establish the account. After the first payment has been received, the promo code will be applied as a credit that will be used until the credit has been used up. After that, normal billing will proceed using credit billing information.