All Zipcar accounts have the option of being given Zipcar credits for use on future rides and bookings placed on the Zipcar website or on the Zipcar app. You may get Zipcar credits deposited into your account for creating a new account, signing up with one of your friends' referral links, or for redeeming certain promo codes. Your Zipcar credits will be active for 30 days from the moment of deposit. Use your credits as you would regular cash to book rides with Zipcar.