If the non-custodian parent who has not had any rights to our son since 2022 until he takes a court ordered hair follicle drug test claim our son an I not know until now?

[Newtoyouin25]

We are still married but have been separated since 2022 and he lost his rights after he placed a gun to my head in front of our 5 year old son. I think he has claimed our son since 2022 and I am just realizing it. I have had my son for 365 days for 7 years.

[BillM223]

I assume that each year you have entered your son's name and Social Security number.

If anyone else (including spouse on a separate return) uses the same names and SS numbers, the IRS will sooner or later discover this, and communicate with both of you to find out which parent has the right to take the child as a dependent (it sounds like you do).

If you have not received any such communication, then don't worry about it. 

Note that no one at the IRS will tell you who the other person is, if any.