Corresponding angles are congruent if they are formed by a transversal intersecting parallel lines. Not just any two lines will do, so be certain the lines are parallel. As long as the lines are parallel, the corresponding angles with have equal measures, which means they will be congruent.
Corresponding angles are considered congruent, if two parallel lines are incised by a transversal. This makes the same-side interior and exterior angles to be supplementary. Conversely, if the corresponding angles in a transversal of two non-parallel lines, then they are not equal.