Is it ever okay to carry a credit card balance?

Rarely. Credit card interest rates currently average 20–24% APR — one of the most expensive forms of debt available. There is no investment strategy that reliably returns 20%+ per year. Carrying a balance means losing money at that rate every month. The only scenario where it might make sense to temporarily carry a balance is if you are using a 0% promotional APR offer and have a concrete plan to pay the full balance before the promotional period ends. Otherwise, pay your statement balance in full every month. If you cannot, you are spending more than you earn — which is a budgeting problem that needs to be addressed directly.