If you are assigned an IP-PIN (6 digit identity protection PIN) you generally must include it with your e-filed return, or write it next to your signature on a paper return, or else the IRS will not process the return. Your IP pin changes every year, and new one is mailed to you in December or January. Your IP-PIN is not required for your state tax return.
What is supposed to happen if you have an IP Pin assigned and don't include it, is your federal return will be rejected. Your state return may still be accepted and processed. But if both state and federal returns were processed and you have received both refunds, you don't need to do anything else. You may be mistaken about the need for an IP PIN. Or, if the IP-PIN was issued after you filed, you didn't need it this year, but you will need it next year, and it will be different next year.
