I just learned a lesson the expensive way and thought I'd share it with others.
I had a credit card payment due on 3/15/2007 and I paid it on 3/2/2007. I paid next months bill early, on 3/21/2007. This payment was applied as a late pay on the bill due 3/15 and I was charged a $39 late payment fee, even though their records show I had already paid the bill on 3/2/2007. Anyway, this threw all my payments a month behind, what was for this month was being applied as a late payment to last months bill, etc.. A $39 late fee every month...
Anyway, there is a do not pay your bill time between the due date and the closing date. The AT&T card is from CITI, other CITI cards might also automatically add in a late fee if you make a payment between the due date and closing date. Sheesh, I was only trying to pay my bill early! BTW, My minimum monthly payment was ~$21/month, On 3/02 I paid $100 and on 3/21 I paid $330. They did credit me one $39 late fee for March, but I guess I'm stuck with the months after that... Lesson learned - don't pay you credit card bills too early (I have it set up on bill pay now!).