As a little extra info, it used to be standard that the payment due date WAS the next statement date. 30, 31 day grace periods used to be standard. That went away maybe during the 2001 economic downturn.
And for Amex, watch out for very quick temporary authorizations that post the same day. For instance, my closing date is the 8th. I waited for the 8th to make a large purchase, thinking it will post the next statement period. To my surprise, the statement on the 9th included that large charge, which I PIF the next day. This may be due to me almost always PIF the day the statement generates and they knew this.
For now on, if I want float from Amex on a large charge, I wait until the 9th to purchase. On small charges, they've posted on the next statement.
