Penalty and interest will not be imposed if failure to pay any tax was due to death, medically determinable physical impairment, or medically determinable mental impairment. The taxpayer must provide proof of death, medically determinable physical impairment, or medically determinable mental impairment, and pay the taxes within thirty days of the due date. In cases where a fiduciary (legal guardian, committee, conservator) is handling an individual's affairs, the taxes must be paid within 120 days after the fiduciary qualifies or begins to act on behalf of the individual [Virginia Code §58.1-3916].