I used to make about $2K a year doing this, back in the day when the cc's had capped transfer fees and bank interest rates were about 5%. Important caveats: you MUST reserve this money as if it wasn't yours, invest in something that is principal risk free - a short term cd or at the very least a reasonable rate savings like Ally, and be sure to pay the money back before the due date. I can't stress enough that if you can't do that, you shouldn't do this. Even optimally, I'm not sure it's worth the effort at today's rates, though.