When I attempted to place an order on Amazon that would total slightly less than 99% of my Amazon gift card balance, I was unable to do so.
When I placed my cursor over the continue button, I received a message saying "Your gift cards or promotional codes do not cover the full cost of your purchase, please enter another form of payment to continue." I could see from the order total and gift card balance listed that this was incorrect. Since one of the items in my order was a Lightning deal, I needed to quickly solve this problem so I canceled an item I had preordered and completed this order. I then attempted to reorder the item I had preordered and received the same message even though the total was 99.99 and the gift card balance was $101.49. I had Chosen Super Saver Shipping on both orders, and both had Massachusetts as the shipping address so there was no sales tax.
I then contacted Amazon customer service by chat and found out the reason. Amazon now requires you to enter your credit card when your order is over $60 and the total is 60% of the gift card balance. This policy change is not listed in the terms and conditions on their website and I never received notification of the change.
It appears I will need to if I am to continue to make purchases on the site. While this is not a significant problem for me, I imagine it will be a substantial burden for those without debit or credit cards who purchase Amazon gift cards so that they may shop online.