A new study shows the negative impact the Defense of Marriage Act (DOMA), which prevents the military from recognizing the legal marriages of gay troops, has on gay service members and their families.

According to the report, titled Collateral Damage: How the Defense of Marriage Act Harms the Troops and Undermines the U.S. Military and jointly released by the Center for American Progress and OutServe-SLDN, gay troops are denied nearly 100 benefits because of DOMA.

“The Defense of Marriage Act was enacted before same-sex marriage was legal anywhere in the United States,” Katie Miller, author of the report, said in a press release. “Now that nine states have broken down that barrier, it is time that the integrity of all marriages is defended by federal law. No man or woman who dedicates their life to the protection of our country should have to worry about their families being cared for in their absence. Creating two classes of service members is no way to treat our troops and no way to run our military.”

An example given is that of Capt. Matthew Phelps, an officer in the U.S. Marine Corps. Phelps may expect to receive about $20,000 less in benefits and allowances than other married servicemen that he serves beside during an anticipated tour of Okinawa, Japan.

DOMA prevents the military from extending housing and moving benefits, health insurance, and employment assistance to the spouses of gay troops.

“As much as military leaders at all levels may wish to treat the troops under their command with equity, they are forced by federal law to discriminate,” said Allyson D. Robinson, executive director of OutServe-SLDN, which represents LGBT service members. “As a result, gay and lesbian service members are denied access to critical benefits and meaningful support programs the services provides to help families face the unique challenges of military life. This denial weakens the force itself.”