South Carolina State Income Tax Filing: Forms, Deadlines, and Rules Explained

1. What Is South Carolina State Income Tax Filing?

South Carolina state income tax filing is the annual requirement to report taxable income earned during the tax year, when filing thresholds are met, to the South Carolina Department of Revenue (SCDOR). This filing applies to residents, part-year residents, and nonresidents who have South Carolina-source income.

South Carolina state income tax is separate from federal income tax and must be filed even if you have already submitted your federal return to the Internal Revenue Service.

2. Who Must File South Carolina State Income Tax?

You must file a South Carolina state income tax return if you are a resident, part-year resident, or nonresident and your income exceeds South Carolina filing thresholds or if South Carolina tax was withheld. Filing requirements are based on residency status, income level, and the type of income earned.

Quick checklist (common scenarios)

1. South Carolina residents: required to file if gross income exceeds South Carolina filing thresholds or if South Carolina tax was withheld
2. Part-year residents: must report income earned while living or working in South Carolina
3. Nonresidents: must file if they earned income sourced from South Carolina
4. Self-employed individuals: must report South Carolina business or freelance income
5. LLC members and sole proprietors: must file South Carolina returns for pass-through income

3. Your Filing Status and Income Type Decide South Carolina Tax Forms

South Carolina state income tax filing does not use a single form for all taxpayers. The form you must file depends on your residency status and the type of income earned during the tax year. South Carolina uses different forms for residents, nonresidents, and taxpayers with simple income.

Key idea

1. South Carolina resident: files Form SC1040 (Individual Income Tax Return)
2. Part-year resident: files Form SC1040 with Schedule NR
3. Nonresident: files Form SC1040 with Schedule NR for South Carolina-source income
4. Self-employed taxpayer: reports business income on the appropriate South Carolina form
5. Federal return reference: South Carolina filing uses federal income figures as a base

Confirming your residency status and income source early helps ensure accurate South Carolina state income tax filing and reduces the risk of notices from the South Carolina Department of Revenue.

4. Documents Required for South Carolina State Income Tax Filing

Preparing accurate documents in advance helps ensure smooth South Carolina state income tax filing and reduces the risk of delays, notices, or penalties from the South Carolina Department of Revenue.

1. W-2 and 1099 forms: reporting wages, contractor income, or other earnings
2. Federal tax return: Form 1040 used as a reference for South Carolina filing
3. South Carolina withholding records: state tax withheld from income, if applicable
4. Business income records: profit and expense details for self-employed taxpayers
5. Prior year South Carolina return: helpful for consistency and carryforward items

5. DIY vs Accountant vs Managed Filing

Non-US founders usually choose one of three approaches: do it themselves, hire an accountant, or use a managed process. The right choice depends on complexity, time, and risk tolerance.

What typically changes your complexity?

1. Multiple LLCs or multiple partners
2. US-source income / withholding / treaty-related details
3. High bank activity and many transactions

Why founders choose managed filing

1. Fewer missed items and fewer back-and-forth messages
2. Clear checklist + timeline
3. More confidence that forms match the entity type

6. Step-by-Step: How to File South Carolina State Income Tax

Step 1: Confirm your South Carolina residency status

Start by determining whether you are a South Carolina resident, part-year resident, or nonresident. Residency status determines whether you file Form SC1040 or Form SC1040 with Schedule NR, Form SC1040A, or Form SC1040 for South Carolina state income tax filing.

Step 2: Gather income records and federal return details

Collect W-2s, 1099s, and your federal income tax return. South Carolina state income tax filing uses federal income figures as the starting point for calculating state tax.

Step 3: Review South Carolina-specific deductions and withholding

Verify South Carolina tax withheld and applicable deductions, including the South Carolina deduction for federal income tax paid. Accurate withholding information helps prevent balances due or delayed refunds.

Common filing deadline: April 15 for most calendar-year filers

Step 4: Prepare and review the South Carolina tax return

Complete the appropriate South Carolina tax form using the MyDORWAY portal, approved tax software, or professional assistance. Review entries carefully before submission.

Step 5: Submit the return and retain confirmation

File your return electronically or by mail and keep a copy of the filed return, payment confirmation, or refund notice for your records.

Step 6: Plan for next tax year

Maintain organized income and expense records throughout the year to simplify future South Carolina state income tax filing and reduce the risk of errors.

Helpful IRS reference:

• IRS Small Business and Self-Employed resources
• Employer Identification Number information

If you prefer guided assistance, FormLLC can help confirm your South Carolina filing requirements and coordinate the preparation process.

7. Tips to Avoid South Carolina Tax Notices and Penalties

• File your South Carolina state income tax return by the April 15 deadline
• Pay any tax due even if you request an extension to file
• Verify South Carolina tax withholding amounts before submission
• Keep copies of filed returns and payment confirmations
• Respond promptly to any notices from the South Carolina Department of Revenue

8. South Carolina Tax Costs, Penalties, and Filing Timelines

• Filing preparation cost: Varies based on income type and filing method used
• Record cleanup: Optional but helpful if income or withholding records are incomplete
• Late filing penalty: Greater of 10 percent of tax due or $50
• Interest on unpaid tax: Accrues at rates set annually by the South Carolina Department of Revenue
• Filing extensions: Extension to October 15 applies if a federal extension exists or sufficient tax is paid by April 15; the extension applies to filing, not payment

9. Common Federal and South Carolina Tax Forms

1. EIN (Employer Identification Number)

An Employer Identification Number (EIN) is issued by the Internal Revenue Service and is used to identify a business for federal and state tax reporting, including South Carolina state income tax filing for businesses and self-employed individuals.

2. Federal Partnership Return (Form 1065)

Multi-member LLCs file a federal informational return using Form 1065 . Income reported on Schedule K-1 is used to complete South Carolina state income tax returns for individual partners.

3. Federal Corporate Return (Form 1120)

US C-Corporations file Form 1120 at the federal level. Corporate income figures are used to determine South Carolina tax obligations when applicable.

4. South Carolina Individual Income Tax Forms

• Form SC1040 (Form SC1040): Primary South Carolina individual income tax return
• Schedule NR: Required for nonresidents and part-year residents

5. Owner Individual Filing (when applicable)

• Individuals report South Carolina income using Form SC1040, SC1040A, or SC1040 based on residency
• Partners use Schedule K-1 information to complete South Carolina individual returns
• Federal ITIN or SSN may be required for individual South Carolina tax filing

10. Conclusion

South Carolina state income tax filing is a yearly responsibility for individuals and businesses with income connected to South Carolina. Filing accurately and on time helps avoid penalties, interest, and unnecessary correspondence from the South Carolina Department of Revenue.

By understanding South Carolina filing requirements, deadlines, and forms, taxpayers can complete their state returns with confidence. FormLLC provides clear guidance to help streamline the South Carolina state income tax filing process.