(1) Shall not apply with respect to the taxable year in which falls the date of his death or with respect to any prior taxable year ending on or after the first day he served in a combat zone after June 24, 1960;
(2) For a taxable year preceding those specified in paragraph (1) of this Code section which is unpaid at the date of his death including, but not limited to, interest, additions to the tax, and additional amounts shall not be assessed. If assessed, the assessment shall be abated. If any such amount is collected, it shall be credited or refunded as an overpayment.