Wal-Mart is the single biggest U.S. employer outside of the federal government. More than half of its 1.3 million U.S. employees are on its health-care plans. The company said it does not know how many workers would use either of the new benefits.
Wal-Mart's extension of health insurance to domestic partners comes after the U.S. Supreme Court in June forced the federal government to recognize same-sex marriages in states where it is legal. The Supreme Court also paved the way for same-sex marriage in California.
"Since we operate in all 50 states, we thought it was important to develop a single definition for all Wal-Mart associates in the U.S.," spokesman David Tovar said.
Employees' domestic partners can be covered if they are legal spouses, not legally separated; or a domestic partner of same or opposite gender in an ongoing, exclusive relationship similar to marriage for at least 12 months with the intention to continue sharing a household indefinitely, he said.