Amazon didn’t use to allow you to purchase giftcards on their website when using an Amazon gift card (or a gift card balance on your account) but several readers (and this thread on /r/churning) have reported that they are now able to do so. I’m not sure if this is a mistake by Amazon, as this help page clearly states that they cannot be used to purchase giftcards:
There are certain restrictions with Amazon.com Gift Cards, such as not being able to purchase gift cards using a gift card and not being able to transfer them to another account once the claim code has been redeemed
This is another improvement to Amazon gift cards as they now also let you check the balance of a card. If this is a permanent change, it’s pretty huge as a number of cards earn at a high rate at Amazon (although no portal payout sadly) and they are also frequently given out as a gift/reward. Amazon stocks a huge range of third party gift cards, so fingers crossed this is a permanent change and not an oversight.
