I am self employed Can a collection agency file a 1099 and garnish your tax return if the debt is over six years old and the debtor has been in Ohio for six years?

A collection agency has no legal powers. Some agencies are collection attorneys who can file lawsuits. Regardless, no one can seize another person's property without due process according to the persons state of residency laws. In other Words they have to take you to court, win a judgment, execute the judgment, this takes a considerable amount of time. The exception is child support and/or spousal maintenance, or a court order that was already in place.