According to the Path Act, 12/15/15, an ITIN# will expire if not used for a federal income tax return for 3 consecutive years. So how are banks monitoring this? Or is it our responsibility? How are we to know whether a customer has filed 3 consecutive years? What situation would require us to know? I know we would get a new W-8 signed, but what due diligence do we need to know whether the ITIN that is given is still valid?