Please let's not forget that text debt in the US is calculated with penalties and interest retroactively, upon discovery. I absolutely know people that had unknown tax debts (from assets they unknowingly "owned" and got in divorces) pop up, and loom large because of accumulated penalties and interest. (Penalties cannot exceed 25% of the original tax debt, to my knowledge, but I don't believe that interest carries the same cap, and is calculated at the federal short term carry rate + 3%).