Yes you can! The method is called : Balance
transfer. I did it for 2 months in a row. I had no money
to pay my VISA card. However, my Discover card had $1000.00 of
credit available. My Visa card bill wanted a minimum payment of
$300.00. So I transferred $300 from my Discover card (which I was
not using anyway) to my Visa card. The next month, I did not have
money enough to pay all my bills. So I transferred $ again from
Discover to Visa. I did an online Balance transfer.
*NOTE Balance transfers do not
get approved right away. It can take anywhere from 3-14 business
days. Depends on what credit card company it is & depends on
the amount of the transfer. So leave yourself enough time before
the due date of the credit card (you are transferring money to).

