No, defaulting on debt does not result in jail time. In fact, the FDCPA protects consumers from criminal prosecution and jail time even if they fail to pay their debts. However, if the creditor files a lawsuit against you and you fail to respond, this could result in a judge getting involved. If you ignore a debt collection letter from a legitimate agency, there is a chance they could sue you. Should you ignore a court order, a judge could also garnish your wages.