The recent California Supreme Court ruling recognizing same-sex marriages is requiring employers throughout the U.S. to review their plans and make a decision on whether they will extend health care benefits to same-sex spouses.

Most large private employers in California have health care plans that are governed by the Employee Retirement Income Security Act (ERISA), which says that states can’t regulate retirement plans. As a result, some employers may say they don’t have to offer benefits to same-sex partners under ERISA. Others may argue that they don’t have to recognize same-sex spouses under the 1996 Defense of Marriage Act.

To further complicate matters, the California ruling even has implications for out-of-state employers because there is no residency requirement for couples to get married. That means an employee could get married in California, then return to his or her home state and request coverage for their same-sex spouse.

Employers need to review their plans and be clear on how they define a spouse in their plan. They also need to make sure they are clear on tax implications for individuals who are in same-sex marriages.