My statements have shown negative points, and I have had points taken away in the Priority Club Rewards program --- so the bank did take away program miles (not the bank's program, but the hotel chain program). For AA MC, the statement showed negative points, but they didn't take away points from my account --- new purchases just won't earn any points until the point total turns positive again as the previous poster said. If you close the account before you go positive, I'm not sure what will happen. I'm also not sure about the bonuses, but in most cases the bonuses will not be awarded until many months into the future (like 8-10 weeks) --- so if you return, they will not award you the bonus.