It is well documented that most (all?) U.S. Credit Cards don't charge any interest if you pay the bill in full every month. I'm curious how all cards arrived at this common rule, but that's besides the point of my question.
Now suppose you pay only half of the card's balance by the due date one month, because you had some money unexpectedly held up somewhere that you were expecting to have available to you (very timely for my example: let's say you're a government employee impacted by the shutdown, and you made some holiday purchases planning to pay them off with your next paycheck, and you don't have an emergency fund).
And now suppose your cash gets released to you one week after the due date (here my example is not applicable as the shutdown is still on).
Also suppose you use this credit card frequently (every day).
I realize I can stop interest charges at a point in time (not retroactively) on the already outstanding balance simply by paying it off. However, what is the optimal strategy to stop the interest charges on the current month's upcoming expenses (with 3 weeks remaining on the month)?
It is unclear to me whether:
You can just payoff the remainder of the original due amount and move on, or
You have to zero out the current balance (original statement amount plus the last 7 days' worth of purchases), or
You have to zero out the balance AND stop using the card altogether until the next statement date.
The only way to avoid it is to overpay the card by the projected amount of the next 3 weeks' expenses, creating a credit balance that gets depleted by the end of the cycle.