(a) (1) The Franchise Tax Board may grant a reasonable extension of time for filing any return, declaration, statement, or other document required by Part 10 (commencing with Section 17001) or this part in the manner and form as the Franchise Tax Board may determine. Except as provided in paragraph (2), no extension shall be for more than six months.

(2) (A) In the case of a taxpayer residing or traveling abroad, returns shall be filed no later than the 15th day of the sixth month following the close of the taxable year, unless the requirements for extension have been fulfilled on or before that date.

(B) In the case of a partnership required to file a return under Section 18633 or 18633.5, the extension shall be for no more than seven months.

(b) An extension of time granted pursuant to this section is not an extension of time for payment of tax required to be paid on or before the due date of the return without regard to extension. Underpayment of tax penalties shall be imposed as provided by law without regard to any extension granted under this section.