Problem -Checkbox Formula for Several Date Fields for Date that is Prior to or Equal to

I cannot get the box to un-check if the date matches or is before the Actual Date Mail Card. 

[Group - Benefit Period - Mail ID Cards By]  By 12/27/17
[Mail ID Cards By:] 12/28/17
Checkbox - ID Mail Cards past due.

My checkbox field is Mail ID Cards Past Due. I thought if I tell the field what to do if it us true ut would not check the box if the field is equal to or prior to the ID Cards Mail by Date.

My formula is 
If(Today()>[Group - Benefit Period - Mail ID Cards By] or [Mail ID Cards By:]>[Group - Benefit Period - Mail ID Cards By],true)