South Carolina late fee law

8.75%per year

Attaches to the debt by operation of law when you agreed no rate, so it accrues before any lawsuit and can be stated on a demand letter.

8.75% per annum on accounts stated and sums ascertained that draw interest by law, in the absence of a written agreement setting a rate. Separately, § 34-31-20(B) sets post-judgment/money-decree interest at the WSJ prime rate (first edition of the calendar year) plus 4 percentage points, compounded annually. Verified on the official scstatehouse.gov site.

By express written agreement, any rate of interest may be charged - S.C. Code § 37-10-106 caps interest at 6% only on contracts NOT in writing; written contracts may specify any rate (South Carolina abolished general usury caps for written agreements in 1982). Consumer credit remains regulated by the SC Consumer Protection Code (Title 37, with maximum-rate-schedule filing for high-rate consumer creditors); B2B written contracts are effectively uncapped. Verify with counsel.

public+private-construction

Construction (public and private): §§ 29-6-30/29-6-50 - periodic/final payments delayed more than 21 days (owner→contractor) or 7 days after receipt of funds (contractor→subcontractor) accrue interest at 1% per month, but only if the payee notified the payor of the statute at the time of the payment request; on private projects the parties may contract for different rates/periods if §§ 29-6-30 and 29-6-50 are specifically waived by section number in conspicuous bold/underlined type. State procurement: § 11-35-45 - vouchers due within 30 work days; the Comptroller General may levy up to 15% per year on the unpaid balance for the vendor. No general private commercial (non-construction) prompt-payment statute.

Distinctive rules actually found: the 1%/month construction late-payment interest requires advance notice of the statute at the time of the payment request, and private-project parties can opt out only via a conspicuous section-number waiver. Otherwise flat late fees on commercial invoices follow ordinary liquidated-damages/penalty doctrine.