Companies can try to collect a debt almost indefinitely, according to the Federal Trade Commission. However, in practice they are unlikely to be successful after the statute of limitations, allowing them to sue you in order to collect that debt expires. These statutes of limitations vary from state to state.
According to a list of state debt collection statutes of limitations compiled by Bankrate.com, written contract statutes of limitations vary from three years up to a maximum of 15 years. The Bankrate list shows most states impose a different statute of limitations, from three years up to 15 years, on debt from revolving accounts such as credit cards.
Once the statute of limitations governing collection of your debt expires, the debt becomes "time-barred," meaning you can't legally be sued over it. Companies can still attempt to collect the debt after it becomes time-barred by sending you letters asking for payment, but if you ignore the letters there's nothing they can do about it.