One in 10 veterans under the age of 65 is currently living without health insurance and reports not using Veterans Affairs (VA) health care, according to a new study examining health care access for retired service members.

The report, which also found a high number of veterans' family members living without insurance, notes such rates are highest in states that have made little progress in implementing provisions of the Affordable Care Act. These states account for 40 percent of uninsured veterans.

Despite having higher rates of health insurance than the general population, "an estimated 1.3 million veterans lack health insurance coverage and do not use VA health care," noted the study's co-author, Genevieve Kenney, who points out a majority of uninsured veterans tend to be younger and less well educated.

The study, released Thursday by the non-partisan Urban Institute, comes as the nation awaits a Supreme Court decision on the fate of the ACA. A ruling is expected in June.

If upheld, about 630,000 uninsured veterans under the age of 65 would likely qualify for Medicaid, the state and federal health insurance program for the poor, which would be expanded under the law. Under current law, just one in 10 qualifies for the program.

Another 520,000 uninsured vets would be eligible for subsidized health coverage in new marketplaces, or insurance exchanges, mandated under the ACA. This would also benefit close to 80 percent of the nearly one million family members of uninsured vets.

There are currently around 13 million veterans between the ages of 19 and 64 living in the United States. Some 17 percent of those without insurance report suffering from service-related disabilities or functional limitations, while 41 percent say they have unmet medical needs. Another 34 percent say they have delayed care due to cost, the report notes.

With two wars winding down in Afghanistan and Iraq, the findings also showed that one in four uninsured veterans served between September 2001 and 2010.