Charleston County residents who buy their own health insurance will find four insurers on HealthCare.gov again this fall. One of them is new, one is gone, and the plan that sets federal tax credits costs far more.

Open enrollment for 2027 coverage began Nov. 1 and runs through Jan. 15, according to the Centers for Medicare & Medicaid Services. People must sign up by Dec. 15 for coverage that starts Jan. 1, HealthCare.gov says.

The benchmark jumps

For a 40-year-old in Charleston County, the second-lowest-cost silver plan costs $705.07 a month before tax credits in 2027, up from $509.08 this year. That is a 38.5% increase, according to a Charleston Business Report analysis of the individual-market plan files CMS publishes for HealthCare.gov states. Charleston Business Report calculated the benchmarks itself by ranking the silver plans in each South Carolina county by their monthly premium for a 40-year-old and comparing the second-lowest in the 2026 and 2027 files.

That plan matters even to people who never buy it. The premium tax credit is generally equal to the premium for the second-lowest-cost silver plan minus a set percentage of household income, according to the IRS.

Charleston County’s increase was the third-largest among South Carolina’s 46 counties, behind Lee and Greenwood counties. The median county rose 25%. Berkeley County’s benchmark rose 24.8%, to $693.92, and Dorchester County’s rose 26.4%, to $715.04.

Charleston County had one of the cheapest benchmarks in the state this year, ranking eighth-lowest of 46. For 2027 it ranks 30th-lowest.

Part of the jump comes from the loss of the cheapest plans. This year, the two lowest-priced silver plans in Charleston County both came from Molina Healthcare. Molina, which sells 12 plans in the county this year, has no South Carolina plans in the 2027 files. Without Molina’s plans, this year’s benchmark would have been $529.30, and the 2027 benchmark would still be about 33% higher, the analysis found.

Molina is shrinking its marketplace business rather than leaving it entirely. Its enrollees, spread across 14 states this year, will be concentrated in six states in 2027, its chief executive said in July, Healthcare Dive reported.

For 2027, the benchmark in Charleston County is Ambetter from Absolute Total Care’s Streamlined Silver SC plan.

Who is selling

Charleston County will have 62 plans in 2027, up from 60. BlueCross BlueShield of South Carolina offers 23 of them, Ambetter from Absolute Total Care 17, Oscar Health Plan 14 and First Choice Next eight.

Oscar is selling marketplace coverage in South Carolina for the first time, Healthcare Dive reported. The federal files list Oscar in six counties: Charleston, Colleton, Florence, Horry, Marion and York.

Oscar is not selling in Berkeley or Dorchester counties. With Molina gone, both drop to three insurers and 48 plans, from four insurers and 60 plans this year.

BlueCross is also dropping a type of plan. This year it sells nine BlueExtend PPO plans in Charleston County. The 2027 files list no PPO plans anywhere in South Carolina, so every plan in the county is an HMO or an EPO. Those plans generally cover care only from providers in the plan’s network, except in emergencies, according to HealthCare.gov.

What people will pay

Prices rose across the board. The cheapest bronze plan for a 40-year-old in Charleston County, BlueCross’s Blue Cooper Bronze 2, goes to $506.47 a month from $390.54, a 29.7% increase.

People who get tax credits are partly shielded, because the credit grows with the benchmark. Under the IRS formula, a wider gap between the benchmark and a cheaper plan leaves more of the credit to apply to that cheaper plan. For a 40-year-old in Charleston County, the gap between the benchmark and the cheapest bronze plan widens to about $199 a month in 2027, from about $119.

People who earn too much for a credit pay the full price. The credit is generally limited to households with incomes up to 400% of the federal poverty line, according to the IRS, which says Congress temporarily expanded eligibility for tax years 2021 through 2025.

Sign-ups for 2026, the first year after that expansion ended, dipped slightly in the Charleston area. In Charleston County, 51,103 people picked a marketplace plan during open enrollment for 2026, down from 51,810 a year earlier, according to CMS county-level data. About 83% of them received advance tax credits.

Their average premium after credits rose to $169 a month, from $109 a year earlier. The number paying $10 a month or less after credits fell to 13,697, from 25,950.

Berkeley County had 26,975 plan selections for 2026 and Dorchester County had 17,934, each down about 2% from a year earlier. Across South Carolina, 587,567 people picked plans, down from 631,948, CMS data show.

Shopping for 2027

Nationally, KFF projects that marketplace premiums will rise about 13% on average in 2027, The Associated Press reported. CMS said in an Oct. 30 fact sheet that more than 75% of HealthCare.gov enrollees will have access to premiums of $50 or less in 2027.

The 2027 Charleston County list also includes a BlueCross catastrophic plan, BlueEssentials Catastrophic 1, priced at $462.02 a month for a 40-year-old. The county had no catastrophic plan this year.

People who enroll or switch plans between Dec. 16 and Jan. 15 will have coverage that starts Feb. 1, according to HealthCare.gov.

The figures in this story are full monthly premiums for a single 40-year-old before tax credits, unless otherwise noted. Actual prices vary by age, household and income.