Under Gov. Nikki Haley, South Carolina decided the state will not expand Medicaid eligibility under the Affordable Care Act, but the low-income health insurance program is growing here anyway — even faster than in many states that are expanding Medicaid eligibility rules.

A new federal report published Tuesday shows that the number of Medicaid applications submitted to the S.C. Department of Health and Human Services in October was 20.2 percent higher than recent monthly averages.

More than 32,000 Medicaid applications were submitted in South Carolina in October, compared with an average 27,000 in previous months, according to the federal report prepared by the Centers for Medicare & Medicaid Services.

That rate is higher than those of most other states that also opted out of the Affordable Care Act’s Medicaid expansion, and it’s higher than those of many states that are expanding their programs. The average growth among all non-expansion states was 4.1 percent in October. The average growth among states that are expanding Medicaid was 15.5 percent in October.

“Both South Carolina and Virginia attribute their increased application number not only to awareness about new coverage opportunities, but also the increased use of their online applications,” the federal report said.

Virginia’s Medicaid application rate jumped 22.5 percent in October, according to the report. Like South Carolina, Virginia is not expanding its Medicaid program under the federal law.

The South Carolina Medicaid agency launched the state’s first-ever online Medicaid application Oct. 1 because it was required by federal law. Many states already allowed Medicaid patients to enroll online.

S.C. Medicaid Director Tony Keck said some of the increase can be explained because residents who were previously eligible for Medicaid but not enrolled in it are now signing up for coverage.

“We’ve got this huge population of eligible but unenrolled individuals that have been eligible for Medicaid for many, many years but have never been enrolled in the program,” Keck said. “There are many states where that number is not as big.”

The expanded rolls, among other reasons, are expected to add nearly half a billion dollars to the state’s $6.5 billion Medicaid agency budget next year, Keck said.

The Affordable Care Act establishes several ways for uninsured Americans to enroll in a policy. Millions are expected to shop for a plan on the federal marketplace. Low-income individuals in certain states qualify for Medicaid if they earn up to 138 percent of the federal poverty level, less than $16,000 a year for a single adult. South Carolina is not accepting federal money to expand Medicaid, so the eligibility rules here won’t change.

In South Carolina, childless adults without a qualifying health condition cannot enroll in Medicaid, regardless of their income.

If the state were to choose to expand the program under the Affordable Care Act, the Medicaid agency estimates about 344,000 newly eligible South Carolina residents, including adults without children, would qualify for coverage.

More than 1 million South Carolinians already carry Medicaid cards. The agency expects more than 100,000 residents who are currently eligible but not enrolled in Medicaid will sign up between Oct. 1, 2013, and January 2015.

Preliminary November enrollment data provided by the state agency shows 25,200 Medicaid applications were submitted last month.

Reach Lauren Sausser at 937-5598.