If a joint return is made under Revenue and Taxation Code Section 18522, any election, other than the election to file a separate return for the taxable year with respect to the treatment of any income, deduction, or credit of such spouse, shall not be changed in the making of the joint return where such election would have been irrevocable if the joint return had not been made. Thus, if one spouse has made an irrevocable election to include patronage dividends in gross income for the year received under Revenue and Taxation Code Section 17086, this election may not be changed upon making the joint return under Revenue and Taxation Code Section 18522.