Couples may change from joint returns to separate returns only:

A. prior to the due date for the return.

B. subsequent to the due date for the return.

2. Couples may change from separate returns to a joint return within:

A. one year of the due date including extensions.

B. two years of the due date including extensions.

C. three years of the due date including extensions.

D. four years of the due date including extensions.