Yes! If you already subscribe to the SHOWTIME streaming service directly through SHOWTIME.com you will be able to apply the entire amount of your SHOWTIME gift to your existing account as a credit. Once applied, the cost of your subscription will be deducted from the available credit. Any remaining credit will be applied to future subscription periods until the credit has been used up.
Gifts can only be applied to an individual subscription to the SHOWTIME standalone streaming service billed directly by SHOWTIME in the United States. SHOWTIME gifts cannot be applied to subscriptions started through other billing partners (Amazon, Android, Apple or Roku), add-on subscriptions through Amazon Video, DIRECTV NOW, Hulu, PlayStation Vue, Sling TV or YouTube TV, or subscriptions through cable, satellite or telco operators.