Under the Post-9/11 GI Bill, the federal government will pick up the full in-state cost for any honorably discharged servicemember wishing to attend a public college or university. However, because the often intricate rules governing residency differ from state to state, and even within university systems, many veterans face a bewildering battle to exercise the benefits they've already fought for.

"It is part of our contractual agreement when we join the military," said Perez, who filed a $10 million federal civil rights lawsuit against the University of North Carolina Board of Governors after one of its schools denied her resident status. "It's been paid for -- with blood and sweat and tears and deployments."

Until last year, the Department of Veterans Affairs would cover up to the highest rate charged for in-state students at a public school in that state. But under changes that took effect in August 2011, while veterans can receive up to $17,500 a year for study at private schools, the agency will pay only "the actual net cost for in-state tuition and fees assessed" by the public institution the veteran is attending.

And if that person is deemed a nonresident, the veteran often must pay the difference out of pocket.

"For the first time since the inception of the GI Bill, residency for tuition purposes is now an issue for thousands of veterans," said Jason Thigpen, founder and president of the Student Veterans Advocacy Group. "Invariably, many are left with no home state for tuition purposes as a result of this change."

Army Staff Sgt. Stephen Lee was still in Afghanistan -- his second deployment to the war zone -- when he began looking at colleges. The California native settled on the University of Wisconsin-Madison and had already begun his studies when he learned of the coming changes to his GI Bill benefits.

He was looking at an extra $20,000 a year out of pocket.

"It was a HUGE jump," said Lee, whose military occupational specialty, or MOS, was human intelligence collector. "And that's when I had to start thinking really hard about whether or not I was going to be able to afford school, or whether I'd have to take a year off and work while I tried to get in-state status."

Around that time, the university opted into the Yellow Ribbon Program, a provision of the GI Bill under which the school and the VA agree to split the difference between the resident and nonresident rate. There was only a limited amount set aside for the program, and students have to reapply each year, but Lee lucked out.

"This uncertainty almost took me out of school," he said. "California's not home for me anymore. At the same time, I didn't have any choice of living in Kentucky or Tennessee. That's where the Army told me I was going. You're kind of in this limbo where you don't know where your state residency lies."

He graduated in May with a bachelor's degree in political science.

Hayleigh Perez's case is a prime example of how convoluted these situations can become.

Perez, 26, enlisted in 2005 and was stationed at North Carolina's Fort Bragg, where she trained as a radiology technologist. She later did a 15-month deployment to Camp Bucca, Iraq.

While serving, the Iowa native met and married Sgt. 1st Class Jose Perez-Rodriguez, a medic, and the couple bought a home in Raeford, near the North Carolina base. Perez's next assignment took her to Texas, where she mustered out of the service in 2009.

When Perez learned in late 2011 that her husband's orders would bring the family back to North Carolina, where they had continued paying property taxes, she began applying to schools. She was accepted at Fayetteville State University and UNC-Pembroke.

However, while FSU granted her resident status, Pembroke -- which had the courses she most required -- classified her as an out-of-state student. The difference in her out-of-pocket costs: $4,603.50 per semester.

When Perez's appeal to UNC was denied, she and Thigpen's group sued.

"Mrs. Perez provided ample evidence to both UNC System Schools in order to substantiate her domicile as a resident in and of the State of North Carolina," stated the lawsuit, filed Nov. 8. "Mrs. Perez filed for a residency appeal hearing with UNC Pembroke, was denied any representational assistance and in turn her appeal was denied after being treated with malice and contempt by UNC Pembroke officials ... ."

The university system has not responded to the complaint, but spokeswoman Joni Worthington denied discrimination against Perez or any other veteran.

"We certainly believe that the university has complied fully with federal and state law," she said. "On the contrary, we have demonstrated a strong commitment to be very supportive of the military, which is obviously very important here in North Carolina."

Under North Carolina law, active-duty servicemembers stationed here are to be considered residents. Perez, however, already had been discharged by the time she was accepted at the schools and had not yet been back the requisite year.

"The burden of proof is on the student," Worthington said.

Worthington agreed that because of the GI Bill changes, "recipients are financially disadvantaged if they choose to attend a public institution of higher education. We believe the level of tuition benefits available at private institutions should apply to public institutions, as well."

Last year, Thigpen's group helped draft the Veterans Education Equity Act, which would amend Title 38 to extend the $17,500 tuition cap to public institutions. The bill never got beyond subcommittee hearings.

Some states already have decided to act on their own.

According to Student Veterans of America, nine states have passed legislation to offer in-state tuition rates to veterans, regardless of how long they've lived there. Five other states have legislation pending, said Mike Dakduk, the group's executive director.

In 2011, Arizona amended its laws to grant veterans "immediate classification as an in-state student" "while in continuous attendance toward the degree for which currently enrolled," and "demonstrated objective evidence of intent to be a resident of Arizona." The Rhode Island Board of Governors for Higher Education changed its rules in 2009 to grant all veterans in-state status.

"These courageous men and women have made great sacrifices in leaving behind their families, their jobs and all that is familiar to them in life to serve our state and our nation," chairman Frank Caprio said at the time. "These veterans deserve our admiration and respect, and aiding their efforts to secure a college degree is one small way we can and should show our appreciation for everything they have done."

In Texas and Wisconsin, veterans who were residents at the time of enlistment retain permanent in-state tuition eligibility in the state university system. The Illinois Veteran Grant program pays for up to 120 credit hours of tuition, but veterans must have lived in Illinois at the time of enlistment and have returned to the state no more than six months after discharge.

Lawmakers introduced a bill in California's General Assembly last February to grant veterans with at least three years' service one year's worth of resident status so they can begin their studies immediately. It died in the appropriations committee without even coming up for a vote.

Veterans can attend Connecticut's state schools tuition-free, provided they've lived in the state at least a year upon enrollment. An attempt in 2011 to amend that requirement failed. At the University of Connecticut, though, a veteran seeking a tuition waiver need only "be domiciled in Connecticut at the time of acceptance."

In Iowa, resident status is left up to each school's board of regents.

Dakduk said this patchwork of rules has left a lot of veterans bewildered, to the point where many either pay the difference out of pocket, take out loans or just give up.

"By and large, veterans don't complain about it," he said. "They kind of just suck it up and move forward."

Justin Curley refused to just suck it up.

The Missouri native was a medic in the Air Force. Like many veterans, though, he learned that those skills didn't automatically translate to a job in the civilian world.

After leaving the service in 2009, Curley moved to New Orleans and applied to the nursing program at Delgado Community College, but because he hadn't been employed in the state for at least one year, the chancellor denied him in-state status.

Curley took out loans to cover the difference, about $3,000 a year, but a friend convinced him to fight, and he launched a petition drive on the website change.org.

"Essentially, because I constantly moved with the Air Force, the Louisiana Community and Technical College System is taking away the veterans benefits I rightfully earned in favor of unwritten policies that are left up to the discretion and judgment of the board and chancellor," he wrote. "To me, that says I'm a resident of nowhere. All because of my service."

In October, Curley met with newly installed Chancellor Monty Sullivan. Not only did Sullivan grant Curley the in-state rate, he refunded his money back to fall 2011.

Curley said recruiters tell a lot of "half-truths" to convince people to enlist, but the most important promise -- that of an education -- shouldn't come with strings, he said.

"There wasn't any fine print," said Curley, 30, who has two more semesters before getting his registered nurse certification. "There wasn't any, 'Well, IF you're considered in-state,' 'IF you're not considered in-state, 'You MIGHT have to pay this,' 'You MIGHT have to pay that.' There wasn't like some little quiet announcer guy in the background saying there are going to be all these stipulations. We were just told this is what it's going to be. ...

"If we contributed to the security of our country, isn't that worth more than having lived in a state in a year?" he asks. "It just seems kind of silly."

In a follow-up email, Worthington said that, because Perez-Rodriguez is currently stationed in North Carolina, Perez "would be considered an in-state resident were she to re-apply to a UNC institution now." Perez argues that she had already established residency based on her own active-duty service in North Carolina.

Perez dipped into her 3-year-old daughter's college fund to pay for one semester at Pembroke but has since transferred to Methodist University in Fayetteville, a private school. She said the government is covering the entire cost.

Her original plan was to become a physician's assistant. Now, she's going for a master's degree in public policy.