The below summary is excerpted from
McDermott, Will and Emery:
The California state legislature recently enacted a law that may affect the taxation of benefits an employer provides to same-sex domestic partners in the state. California AB 362 excludes from gross income for California state income tax purposes the amount of any tax gross-ups paid by an employer to an employee for benefits for that employee’s same-sex spouse or domestic partner. The law was approved by California’s governor on October 1, 2013, and is effective immediately through January 1, 2019. ...
As a result of Windsor and the subsequent IRS guidance, the impact of California AB 362 appears fairly limited. Pre-Windsor, some employers provided a federal tax gross-up on the imputed value of coverage provided to an employee’s same-sex spouse or domestic partner. Post-Windsor, same-sex married couples in California no longer need a tax gross-up for either state or federal tax purposes because they no longer have to be taxed on the value of the coverage provided to their spouse. Because of this treatment, application of California AB 362 would be limited to a situation where an employer provides a federal tax gross-up to an employee who is in a California-registered domestic partnership. Such a gross-up, which would have been taxable under prior state law, is now no longer taxable in California. Employers in California will need to update their payroll and tax procedures accordingly. Employers both inside and outside of California that previously provided tax gross-ups may find it desirable to revisit their gross-up policies in light of theWindsor decision and the IRS guidance.