Will Arnett Files for Divorce from Amy Poehler

This is not a trick, Michael -- "Arrested Development" star Will Arnett has officially filed for divorce from Amy Poehler ... nearly two years after the couple separated.

According to court documents, Arnett wants joint legal and physical custody of their two sons aged 5 and 3. He also wants visitation.

43-year-old Arnett and 42--year-old Poehler got married in 2003.

Since they separated, Arnett has reportedly been dating Billy Joel's ex-wife Katie Lee and Poehler has been linked to comedian Nick Kroll.