Now that same-sex marriage has been legalized in New York, at least a few large companies are requiring their employees to tie the knot if they want their partners to qualify for health insurance.

Corning, I.B.M. and Raytheon all provide domestic partner benefits to employees with same-sex partners in states where they cannot marry. But now that they can legally wed in New York, five other states and the District of Columbia, they will be required to do so if they want their partner to be covered for a routine checkup or a root canal.