Consultants in South Carolina: taxes and retirement for 2026
For independent consultants and fractional executives billing clients directly in South Carolina. South Carolina has a graduated state income tax for 2026: 1.99% to 5.21% (top rate starts at $30,000 for single filers). Here are the 2026 rules, a worked example and the official sources.
South Carolina rules for consultants
- State income tax (2026)
- South Carolina has a graduated state income tax for 2026: 1.99% to 5.21% (top rate starts at $30,000 for single filers). H. 4216 (signed March 30, 2026) applies from tax year 2026. Income under $30,000 is taxed at 1.99%; income of $30,000 and up is taxed at 5.21% minus $966, which works out to 5.21% on income above $30,000. It replaces the federal standard deduction with a South Carolina Income Adjusted Deduction ($15,000 single) and caps the state EITC at $200. The top rate can drop further if revenue growth triggers are met.
- State estimated tax
- You must file a declaration of estimated tax if you expect to owe $100 or more in income tax when you file your return. Same dates as federal (April 15, 2026; June 15, 2026; September 15, 2026; January 15, 2027) Form SC1040ES.
- Common-law test for unemployment insurance (S.C. Code § 41-27-230)
- For unemployment insurance, a worker counts as an employee if they are one under the usual common-law rules on employer control. Certain agent-drivers and traveling salespeople are also covered.
Federal rules for 2026
Solo 401(k) up to $72,000
A one-person consultancy can contribute a $24,500 employee deferral plus an employer share of about 20% of net self-employment earnings, up to $72,000 in 2026, plus an $8,000 catch-up at 50 or older ($11,250 at ages 60 to 63).
The S-corp trade-off
Electing S-corp status can cut payroll tax, but the salary you pay yourself also sets your Solo 401(k) room. Run both sides before you elect.
Quarterly estimated taxes
No one withholds tax from self-employment income, so you generally pay estimates four times a year if you expect to owe $1,000 or more. For 2026 income the federal dates are April 15, June 15 and September 15, 2026, and January 15, 2027. Paying 100% of last year's tax (110% if your AGI was over $150,000) in four equal installments avoids the underpayment penalty.
Self-employment tax
On top of income tax, self-employed people pay 15.3% on 92.35% of net profit: 12.4% Social Security up to the 2026 wage base of $184,500, plus 2.9% Medicare with no cap. Half of it is deductible.
A worked example
| Self-employment tax (sole proprietor) | $21,194 |
|---|---|
| Solo 401(k) maximum | $52,381 |
| SEP IRA maximum | $27,881 |
| Payroll tax saved as an S-corp on a $75,000 salary | $9,719 |
| Solo 401(k) maximum as that S-corp | $43,250 |
Federal figures only, before state and local taxes. Simplified: excludes the QBI deduction and the 0.9% Additional Medicare Tax. Computed from 2026 IRS limits (Notice 2025-67, Rev. Proc. 2025-32) and the SSA wage base.
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Questions
Do consultants in South Carolina pay state income tax?
South Carolina has a graduated state income tax for 2026: 1.99% to 5.21% (top rate starts at $30,000 for single filers). H. 4216 (signed March 30, 2026) applies from tax year 2026. Income under $30,000 is taxed at 1.99%; income of $30,000 and up is taxed at 5.21% minus $966, which works out to 5.21% on income above $30,000. It replaces the federal standard deduction with a South Carolina Income Adjusted Deduction ($15,000 single) and caps the state EITC at $200. The top rate can drop further if revenue growth triggers are met.
When are South Carolina estimated tax payments due for 2026?
You must file a declaration of estimated tax if you expect to owe $100 or more in income tax when you file your return. Same dates as federal (April 15, 2026; June 15, 2026; September 15, 2026; January 15, 2027) The state form is SC1040ES.
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Sources
- dor.sc.gov/news/information-about-h-4216
- dor.sc.gov/sites/dor/files/forms/SC1040ES_2026.pdf
- www.dol.gov/agencies/whd/state/minimum-wage/tipped
- www.scstatehouse.gov/code/t41c027.php
State and local facts researched from official sources and independently re-checked; last verified October 2026, next scheduled review 2027-01-02. Educational information for 2026, not tax, legal or investment advice. Rules change; check the official sources listed and a tax professional for your situation. Gigaverse AI, Inc. is a financial technology company, not a bank, and not itself a registered investment adviser or broker-dealer.