North Carolina and South Carolina each run their own sales tax system with separate registrations, separate returns, and separate rules. If you sell into both, you have two compliance obligations, not one. The mistake we see most often is a business that registers in its home state, ignores the other, and gets a nexus letter eighteen months later asking for back taxes, penalties, and interest.

Start with registration. Physical nexus triggers immediate registration in either state. That includes an office, employees, inventory in a warehouse (including third-party fulfillment), a sales rep visiting customers, or even attending trade shows depending on activity. North Carolina issues a Certificate of Registration through NCDOR. South Carolina requires a Retail License through SCDOR. These are two separate applications with two separate account numbers.

For remote sellers without physical presence, both states use a $100,000 in-state gross sales threshold for economic nexus. North Carolina dropped the 200-transaction test in 2024, and South Carolina also uses gross revenue only. Track your sales into each state continuously. The trigger date is when you cross the threshold, and you generally need to register and begin collecting by the next month or the start of the next calendar year depending on circumstances.

Local rates are where this gets complicated. North Carolina has a 4.75% state rate plus county rates that bring most combined rates to 6.75% or 7%, with a few counties slightly higher. South Carolina has a 6% state rate plus local option taxes that can push combined rates to 9%. South Carolina’s local rate structure includes school district taxes, capital projects taxes, and transportation taxes that differ by county. Manual rate lookup is not realistic at any reasonable sales volume. Most clients use TaxJar or a similar engine to assign the correct destination rate per transaction, and our sales tax management service is built around that workflow.

Marketplace facilitator rules cover both states. If you sell through Amazon, Etsy, Walmart, or eBay, the marketplace collects and remits sales tax on those orders. You still need to know which sales were marketplace versus direct, because direct sales from your own website remain your responsibility. Many sellers also still need to file zero or informational returns even when the marketplace handles the tax, depending on registration status. Don’t assume marketplace coverage means you can skip registration entirely.

Exemption certificates are state-specific. A North Carolina Form E-595E does not exempt a South Carolina sale, and an SCDOR ST-8 or ST-9 does not work in North Carolina. If you sell to wholesalers, resellers, manufacturers, or nonprofits, you need the correct certificate from the correct state on file before the sale, dated and signed, with the buyer’s permit number. Multistate uniform certificates exist but acceptance varies, so confirm before relying on them.

Filing calendars run independently. Both states assign monthly, quarterly, or annual filing frequency based on tax liability, and both generally require returns by the 20th of the month following the period. The catch is that your assigned frequency in one state may not match the other, and the states don’t communicate. We’ve seen clients file North Carolina on time and forget South Carolina because the period ended on a different schedule. Set separate calendar reminders and treat each state as its own track.

Beyond sales tax, watch state income tax. Doing business in both states usually creates income tax filing obligations in each, with apportionment based on sales, payroll, and property factors. Pass-through entities have additional considerations with the elective pass-through entity tax in both states, which can be a real federal tax saving if elected correctly. That’s worth a planning conversation rather than a default decision.

If you’re operating across the Carolinas and the compliance is starting to outpace what you can manage in-house, that’s exactly the work our bookkeeping, tax and consulting services are built to handle. Two-state sellers need someone tracking nexus, rates, filings, and exemptions on an ongoing basis, not just at year end.