However, some employers are starting to "gross up" employees' salaries to offset the imputed income tax. As of March 2012, the Human Rights Campaign Foundation knew of 36 for-profit employers with a policy of grossing up. Last June, Cambridge, Mass., became the first municipality to gross up city employees' benefits.
• Taxes: Each taxpayer in an unmarried couple can take only half the exemption of a married couple. For some couples, this makes little difference in their tax liability, but for others, the difference can be substantial. For instance, if one person is working while the other raises children or finishes school, that couple will often owe higher taxes than a couple who is married, filing jointly, according to Goch. She adds that same-sex couples also miss out on deductions such as alimony.
To further complicate matters, some states require registered domestic partners to split their income for state tax purposes, while the federal government requires those taxpayers to file separately. Running both sets of numbers requires more time and often more money for a financial professional, says Koch.
• Estate planning: The property issues mentioned above are only one aspect of estate planning. Making sure a partner is named as the primary beneficiary on life insurance or retirement accounts is especially important for same-sex couples, because without beneficiary forms, assets will pass to a parent or other relative rather than the partner. Beneficiary forms are more powerful than a will or trust, adds Goch.
Unmarried partners also run into issues with inheriting retirement accounts. "In a traditional marriage, your spouse can do a 401(k) rollover and it's not taxable," says Goch. "But when you're in a same-sex partnership, it's going to force a lump-sum distribution that's all taxable if it goes through your trust." Partners who are named as beneficiary on a retirement account would have to begin taking distributions immediately, whereas a widowed spouse has more flexibility.
"Every couple is unique because some might have families that are very unfriendly towards the relationship so they know they need to protect themselves," says Koch. "Others have very supportive families. Either way, you're best served by getting very savvy on these issues or consulting experts."