Because same-sex marriage is recognized by the federal government, same-sex couples now have access to some estate tax benefits that traditional couples have enjoyed for years. These benefits can help reduce the federal tax burden related to both estates and gift-giving.
The benefits come from the fact that spouses are allowed to combine, or share, some of their exclusions with relation to taxes. Consider the gift exclusion: federal law allows someone to gift an amount up to $14,000 per calendar year to another person without paying a gift tax on that amount. If you are married, though, you can give a gift to someone with half of it coming from you and half coming from your spouse -- no matter where the money actually originates from. That means you could gift a single person $28,000 -- half on behalf of yourself and half on behalf of your spouse -- without worrying about gift taxes.
Marriage benefits also extend to the federal estate tax. For a single person, the threshold of estate value before you have to pay federal taxes is $5.45 million as of 2016. If you are married, you can pass on unused portions of this exclusion to your spouse. So, if one spouse passes away with an estate valued at $2 million, the surviving spouse could pass away with an estate valued at $8.9 million ($5.45 million plus the remaining $3.45 million from the other spouse's exclusion) before federal estate tax was relevant.
In many cases, federal estate taxes won't apply to money left between spouses, depending on how those assets were treated during the estate planning process. Same-sex couples who are taking advantage of federal laws to get married should also talk to an estate lawyer to understand how marriage can change future financial and tax planning.