Your county changes which rating area your South Carolina small group rate is built on, and in this state the county is the whole of the geography — but it is the county attached to one address, not the county each employee lives in, and no source read for this page publishes a price for any area. South Carolina draws 46 rating areas, one per county, for all 46 counties. That makes the geographic question unusually simple to answer and unusually easy to answer wrong, because four of the state’s biggest markets are cities that straddle county lines and therefore sit in more than one rating area at once.
South Carolina draws its rating areas on county lines, and only on county lines
CMS publishes the state’s geography under the heading “South Carolina Geographic Rating Areas: Including State Specific Geographic Divisions,” introduced by the sentence “the state specific geographic rating areas, including specific geographic divisions for the Individual and Small Group market in South Carolina are:”. The table that follows has three columns — a rating area identifier for federal systems, a county name, and a zip column CMS heads “3 Digit Zip Code”
, marked “if applicable” — and 46 data rows.
The zip column is the interesting one. It is present in the header and empty in every single row: no South Carolina county is split by zip code. Distinct rating area labels equal distinct county names equal the row count, so every county sits in an area of its own and shares it with no other county.
Two things about vintage, stated plainly because the difference matters. The CMS page carries an in-page stamp reading “Page Last Modified: 09/10/2024.”
It states no effective plan year anywhere on the page. This page therefore attributes the table to CMS with that modification date and asserts no plan year for it, because none was published to assert.
Four of South Carolina’s seven most-named markets sit in more than one rating area
Here is the fact that undoes the shortcut. A South Carolina city is not a rating area, and several of the biggest ones are not even inside a single rating area.
Charleston spans Charleston and Berkeley counties, which are two separate rating areas. The city is one of the state’s statutory seaports — S.C. Code §54-3-110 names “the harbors or seaports within the State, namely Charleston, Georgetown, and Jasper,” and directs the State Ports Authority to develop and operate the harbor along with its terminal railroads and belt line roads. The harbor economy that authority serves runs on past the county line, and the rating geography changes when it does.
North Charleston spans Charleston, Berkeley and Dorchester counties — three rating areas. S.C. Code §54-3-117 directs the Ports Authority to “take all action necessary to expeditiously complete construction of a container terminal in North Charleston,” and the precincts of North Charleston are listed among the voting precincts of Charleston County. Neither of those facts fixes the city inside one rating area, because the city itself does not sit inside one county.
Columbia spans Richland, Lexington and Kershaw counties. Two of those are joined for another purpose entirely: §55-11-310 constitutes the territory of Richland and Lexington counties as the Richland-Lexington Airport District, a political subdivision of the State, and §55-11-320 gives the City Council of Columbia appointments to its commission alongside the two county legislative delegations. That district is administered as one unit and rated as more than one. It is a clean illustration of the general point — the boundaries South Carolina uses to govern a labor market and the boundaries it uses to rate insurance were drawn for different reasons and do not line up.
Florence spans Florence and Darlington counties. The regional structure nearby runs differently again: §55-11-610 constitutes the territory of Florence, Marion and Dillon counties as the Pee Dee Regional Airport District, each of those three being a rating area in its own right. Note the vintage trap on that one — a 1998 amendment deleted Darlington County from the district, so any source older than June 1998 names four counties instead of three.
Greenville, Spartanburg and Rock Hill are the three of the seven that sit wholly within one county — Greenville, Spartanburg and York respectively. Even here the surrounding structures cross lines: §55-11-110 constitutes the territory of Greenville and Spartanburg counties as the Greenville-Spartanburg Airport District, so two markets in separate rating areas share one body politic.
One address decides it, and federal rule says which address
The resolution is federal rather than municipal, and it is worth quoting because it settles the question a multi-site employer always asks. 45 CFR 147.102(a)(1)(ii)(B):
“In the small group market, using the group policyholder’s principal business address. For purposes of this paragraph (a)(1)(ii)(B), principal business address means the principal business address registered with the State or, if a principal business address is not registered with the State, or is registered solely for purposes of service of process and is not a substantial worksite for the policyholder’s business, the business address within the State where the greatest number of employees of such policyholder works. If, for a network plan, the group policyholder’s principal business address is not within the service area of such plan, and the policyholder has employees who live, reside, or work within the service area, the principal business address for purposes of the network plan is the business address within the plan’s service area where the greatest number of employees work as of the beginning of the plan year. If there is no such business address, the rating area for purposes of the network plan is the rating area that reflects where the greatest number of employees within the plan’s service area live or reside as of the beginning of the plan year.”
One address governs the whole group. Not each employee’s home county, not an average across worksites, and not where the business colloquially “is.” The cascade exists for the awkward cases — a registered address that is only a registered agent’s office, or a principal address that falls outside a network plan’s service area — and it resolves each of them to a single address, and therefore a single county, and therefore a single rating area.
When your workforce crosses a county line and your rating geography does not
This is where the South Carolina map and the federal rule meet, and it is the section that answers the question in the title for most readers.
An employer in the Charleston harbor economy may draw staff from Charleston, Berkeley and Dorchester counties — three rating areas — and still rate on one. An employer inside the Richland-Lexington Airport District may hold a plant on one side of the district and an office on the other, in two rating areas, and still rate on one. In each case the group has one policyholder address, and that address carries the geography.
The corollary is the part worth acting on. Because the group’s rating area follows one address, moving or re-registering that address moves the group’s rating geography, and opening a second site does not. A Spartanburg County employer’s address fixes its area no matter which side of the North Carolina line its workforce commutes from — and a site moved across that line leaves South Carolina small group rating entirely for another state’s filing regime.
Rating area is one of four permitted factors, and the list is closed
Geography is not the only thing a rate is built on, but the set it belongs to is short and it is shut. Under 45 CFR 147.102(a)(1), the rate “may vary with respect to the particular plan or coverage involved only by determining the following”: whether the plan or coverage covers an individual or family; rating area; age; and tobacco use. Age and tobacco each carry a federally capped band, which this page names as existing without printing the ratio.
Paragraph (a)(2) is the sentence that gives the list its force: “The rate must not vary with respect to the particular plan or coverage involved by any other factor not described in paragraph (a)(1) of this section.”
The provisions apply for plan years beginning on or after January 1, 2014, and do not reach grandfathered health plans.
So the honest answer to “does my county change what I pay” is that your county is one of a very small number of things that is allowed to move the number at all — which is precisely why it is worth getting the address right, and precisely why no one can tell you what that movement is worth from a published table.
South Carolina’s own rating statute names a longer list, and it is older
South Carolina regulates small employer rates through an index-rate and class-of-business mechanism in Subarticle 3 of Chapter 71, §§38-71-910 to -990, enacted by 1991 Act No. 131 and last amended in 1997.
Its factor set is §38-71-920(5): “‘Case characteristics’ means the following characteristics of a small employer, as determined by a small employer insurer, which are considered by the insurer in the determination of premium rates for the small employer: age, gender, geographic area, industry, group size, and family composition. Geographic areas smaller than a county may not be used without prior approval of the director or his designee. Claim experience, health status, and duration of coverage since issue are not case characteristics for the purposes of this subarticle. The adjustment for case characteristics must be objective and meet sound actuarial practices.”
Read the geographic sentence closely, because it is the state-law counterpart to everything above: sub-county geography is not simply available to an insurer in South Carolina — it requires prior approval from the Director. That is the statutory expression of the same coarse geography the CMS table shows.
The tension is plain on the face of both instruments and this page does not resolve it. The 1991 statute names gender, industry and group size as permitted case characteristics. The federal rule permits four factors and closes the list against everything else for individual and small group coverage, for plan years beginning on or after January 1, 2014. Both texts are on the books; South Carolina’s subarticle is unrepealed, carries no sunset and no plan-year clause, and has no ACA conforming amendment. Which instrument governs a particular policy is a legal conclusion this agency does not make. What a buyer can rely on is that a real rate is governed by what the issuer actually files and what the department actually approves.
What the renewal conversation is actually made of
One further piece of the state mechanism is useful even without its figures, because it explains why a renewal number is never a single thing. Under §38-71-940(A)(3), the percentage increase in a renewal premium rate for a new rating period may not exceed the sum of three separately constrained components: the change in the insurer’s new business premium rate across the rating period (or the change in the base premium rate where the insurer is no longer writing new policies in that class); an adjustment attributable to the claim experience, health status or duration of coverage of the employees or dependents, as determined from the insurer’s rate manual for the class; and any adjustment for a change in coverage or in the employer’s case characteristics. Your rating area lives in that third bucket — a change of principal business address is a change in case characteristics.
Around it sit guardrails worth knowing by name. Section 38-71-940(B) requires rating factors, including case characteristics, to be applied consistently across all small employers in a class of business, and §38-71-940(C) prohibits involuntarily transferring a small employer into or out of a class. Section 38-71-960 requires the insurer to disclose its right to change rates, the factors affecting those changes, and a description of the class of business the employer is in. And §38-71-980 is the valve: the Director “may suspend all or any part of Section 38-71-940”
for one or more small employers and rating periods on an insurer filing and a finding about financial condition or market efficiency — so the state constraints should never be described as always applying.
What the table does not say
It is worth being explicit about the negative, because an absence is easy to fill in from imagination. CMS publishes South Carolina rating geography as structure only: an area identifier, a county, and an empty zip column. It returns no premium, no index, no average and no ranking. Nothing read for this page supports a statement that one South Carolina rating area is cheaper or dearer than another, and none is made here.
What is publishable is the map and the rule that reads it. There are 46 South Carolina rating areas and 46 counties, one apiece, and no county is split by zip. Four of the seven most-named markets straddle county lines and sit in multiple areas; three do not. And whichever county your group lands in, it lands there by way of a single policyholder address that federal rule defines with some care.
The bottom line
Your county is South Carolina’s rating geography — one rating area per county, with no county split by zip code. But it is the county of one address, the group policyholder’s principal business address, and not the county each employee sleeps in. No source read here publishes a price by rating area, and nothing on this page says one area is cheaper than another.
Frequently asked questions
How many rating areas does South Carolina have?
Forty-six — one per county, for all 46 South Carolina counties. CMS publishes the table under the heading “South Carolina Geographic Rating Areas: Including State Specific Geographic Divisions,” and the table carries a column for a 3-digit zip code “if applicable” that is empty in every one of the 46 rows. That empty column is the useful part: no South Carolina county is split by zip code, so unlike states that subdivide metro counties, the county is the whole of the geography. The CMS page carries an in-page stamp reading “Page Last Modified: 09/10/2024” and states no effective plan year anywhere, so this page attributes the table to CMS with that date and asserts no plan year for it.
Which county is used if my business has more than one location?
Federal rule decides it, not local practice. 45 CFR 147.102(a)(1)(ii)(B) sets the small group rating area “using the group policyholder’s principal business address,” and defines that as the principal business address registered with the State — or, where none is registered, or where the registered address exists solely for service of process and is not a substantial worksite, “the business address within the State where the greatest number of employees of such policyholder works.” One address governs the whole group. There is a further cascade for network plans: if the principal business address is not inside the plan’s service area and the policyholder has employees who live, reside or work within it, the rating area becomes the in-service-area business address where the greatest number of employees work as of the beginning of the plan year, and failing that, where the greatest number of in-service-area employees live or reside.
Does a South Carolina city sit in one rating area?
Often not, and this is the fact most people get wrong. Because South Carolina rates one area per county, a city that spans county lines sits in more than one rating area. Charleston spans Charleston and Berkeley counties. North Charleston spans Charleston, Berkeley and Dorchester. Columbia spans Richland, Lexington and Kershaw. Florence spans Florence and Darlington. Of the state’s seven most-named markets, only Greenville, Spartanburg and Rock Hill sit wholly within a single county. So “we’re in Columbia” does not by itself identify a rating area — the county attached to the address does.
What can a South Carolina small group rate legally vary on?
Under 45 CFR 147.102(a)(1) the rate may vary only by whether the coverage is for an individual or a family, the rating area, age, and tobacco use — and paragraph (a)(2) closes the list: “The rate must not vary with respect to the particular plan or coverage involved by any other factor not described in paragraph (a)(1) of this section.” South Carolina also has its own rating statute, enacted in 1991 and last amended in 1997, which names a longer set of “case characteristics” at §38-71-920(5): age, gender, geographic area, industry, group size and family composition, while excluding claim experience, health status and duration of coverage from that set. Both instruments are on the books. This page reports that tension and does not assert which one governs a given policy — a reader’s actual rate is governed by what the issuer files and the department approves.
Can an insurer use an area smaller than my county to rate my group?
Not freely under state law. S.C. Code §38-71-920(5) provides that “geographic areas smaller than a county may not be used without prior approval of the director or his designee.” Federally, the rating area is the unit, and CMS’s published South Carolina table draws those units on whole counties with no zip-code subdivision in any row. The practical effect is that South Carolina geography is coarse and legible: you do not have to work out which side of a metro area an address falls on, only which county it is in.
About the author
Nate Jones, CPCU, is the founder of Wexford Insurance and Wexford Health Insurance, an independent agency placing small-business group benefits in 9 states. Wexford Insurance places small group health coverage across South Carolina and works the rating-area question directly, including the multi-county markets where a single city sits in more than one of the state’s 46 county-drawn areas. Start with the Wexford Health Insurance quote form.