Paying the deposit with a Disney Visa gets the 6 months no interest on the deposit. (This applies even for future cruises booked onboard, since they are charged separately and not as part of an onboard account.) If you make another payment with a Disney Visa, the 6 months for that payment starts when it is made, so it is possible to have multiple charges at no interest for different periods of time. This is shown clearly on the credit card statements. If you pay more than your new charges in a month, the excess payment will be applied to the oldest “no interest” charge first. I have had 2 or 3 separate charges listed on my statement.
In order to get the onboard perks — currently, 10% off most purchases of $50 or more in shops, 20% off select port-day spa treatments, 10% off select photo packages, and 10%
Castaway Cay Getaway packages — you must put your Disney Visa on file for onboard charges at check-in. You can, however, go to Guest Services to make payments toward your onboard account using gift cards or Reward cards, as long as you leave your credit card on file.
In the past, it may have been necessary to pay for the entire cruise with a Disney Visa to get perks, such as onboard credits, that were delivered at the beginning of the cruise.