Delta Airlines became the first major airline Thursday to cover the extra income taxes its employees in same-sex relationships have to pay for healthcare plans in states that don’t recognize gay marriage.

The practice, known as “grossing up,” effectively makes it so that same-sex couples pay the same cost of healthcare as legally married employees. The airline said the change will go into effect immediately and cover taxes retroactive to January 1.

Gay marriage is currently legal in 37 states, but Georgia, where Delta is based, is not one of them. That means that Delta executives, flight attendants and pilots in same-sex couples who live in the state have to pay more taxes for the value of their insurance.

See also: Facebook, Google, Apple and others urge Supreme Court to back gay marriage

Delta is not the first company to take such measures. A Human Rights Campaign spokesperson said there are at least 40 large companies and law firms that make employees whole for the tax, but Delta is the first big airline to do so.

The move comes at a time when big businesses are increasingly taking stands for LGBT rights. Earlier this month, nearly 400 companies, including Delta, signed on to an amicus brief urging the Supreme Court to support gay marriage ahead of an April hearing related to a case that could potentially legalize it nationwide.

A number of companies, including Apple, Paypal and NASCAR, slammed an Indiana law that could have given business owners the legal right to turn away LGBT customers, and Salesforce and Angie’s List even went so far as to boycott business in the state. After a week of heavy backlash, Indiana Gov. Mike Pence signed an amendment to the law on Thursday designed to prevent discrimination.

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