With most companies it is 2 months.
However, in the case of fraud, kid stole card, or some other special circumstance. They can give them up to 6 from what I have seen in my experience.
Luckily, I almost never see a charge back or refund. Maybe 1-2 a month of average? However, who and what, and time limit on charge back seems to vary based on processor, and reason given as well as point of contact. The processor for the pay site or the original bank for the credit card..
