Under the provisions of Section 17552 of the Revenue and Taxation Code, the return by a taxpayer who was not in existence throughout a taxable period of 12 months is a return for the fractional part of a year during which the taxpayer was in existence. If a return is required under the provisions of subdivision (a) of Section 18505 of the Revenue and Taxation Code, or for the last taxable year of a decedent, the executor or administrator of the decedent shall file such return at the time prescribed in Section 18566 of the Revenue and Taxation Code. If a return for the last taxable year of an estate or trust is required to be filed under the provisions of subdivision (a) of Section 18505 of the Revenue and Taxation Code, such return shall be filed at the time prescribed in Section 18566 of the Revenue and Taxation Code and the last day prescribed for such filing shall also be the due date for payment of the tax or the first installment thereof.

The executor or the administrator of an estate is required to file returns for the decedent for years prior to the year in which death occurred, if returns for such years should have been filed but have not been filed by the decedent (see Section 18505, of the Revenue and Taxation Code.). Such returns should be filed as soon as possible after the fiduciary has assumed his duties, and, in any event, must be filed prior to the time the estate is distributed (see Article 7, Chapter 4 of the Revenue and Taxation Code for penalty provisions).