SC2220: Underpayment of Estimated Tax by Corporations (2025)
South Carolina · South Carolina DOR · Used for tax years 2025
South Carolina Form SC2220 determines whether a corporation paid enough estimated Income Tax during 2025 and calculates any underpayment penalty. It shows required installments, payments or credits, and underpayments or overpayments for each installment period.
Who files this form
Corporations with an Income Tax liability of $100 or more must prepay their tax through withholding or Estimated Tax payments. This includes S Corporations, LLCs taxed as corporations, and tax-exempt organizations subject to unrelated business Income Tax. Use SC2220 to determine whether enough tax was paid during the year and whether an underpayment penalty applies.
You must file SC2220 with your corporation’s tax return, even if no penalty is due, if you check a Part II box because you are:
- Using the adjusted seasonal installment method.
- Using the annualized income installment method.
- A large corporation calculating its first required installment based on the prior year’s tax.
If the total tax on line 1 is less than $100, the form says not to complete SC2220 and that no penalty is owed.
When it's due
For the 2025 tax year, line 7 lists Estimated Tax installment due dates as the 15th day of the 4th, 6th, 9th, and 12th months of the corporation’s tax year.
For the 2025 penalty calculation, line 17 uses the payment date or the 15th day of the 4th month after the tax year closes, whichever is earlier. SC1120S filers use the 3rd month instead; SC990-T filers use the 5th month.
What you'll need
Have the following information ready:
- The corporation’s name and FEIN.
- The 2025 Income Tax return’s total tax amount: SC1120 line 11, SC1120S line 12, SC1120U line 9, SC1104 line 9, SC1101B line 7, or SC990T line 9.
- The 2024 Income Tax return, if applicable, showing tax after credits and any overpayment elected to be applied to 2025 Estimated Tax.
- Estimated Tax payment amounts and payment dates.
If using the adjusted seasonal or annualized income installment method, use the federal forms, worksheets, and instructions with the necessary South Carolina adjustments. Attach a copy of the worksheet to SC2220. Large corporations and S Corporations are also directed to consult the federal 2220 instructions for specified calculations.
How to file
Attach SC2220 to your Income Tax return. The supplied text does not provide a mailing address or e-file directions.
If you use the adjusted seasonal or annualized income installment method, write “adjusted” or “annualized” to the left of line 8 and attach a copy of the worksheet.
Enter the total penalty from line 36 on line 17 of SC1120, or the comparable line of another Income Tax return.
Common mistakes
- Leaving out SC2220 because no penalty is due: You must still file it with your return if any Part II box is checked.
- Using an ineligible prior-year tax amount: Skip line 2 if the 2024 tax was zero, no return showing a tax amount was filed for 2024, or the 2024 tax year was shorter than 12 months. Use line 1 on line 3 instead.
- Forgetting a prior-year credit: Include any 2024 overpayment elected to be applied to 2025 Estimated Tax on line 9.
- Completing the installment columns out of order: Complete lines 10 through 16 in one column before moving to the next column.
- Omitting the worksheet for a special installment method: Attach the worksheet and label line 8 “adjusted” or “annualized.”
- Stopping after finding an underpayment: If any column on line 15 shows an underpayment, complete Part IV to calculate the penalty.
Questions people ask
What if the corporation’s total tax is less than $100?
The form says not to complete SC2220. No penalty is owed.
How are the regular required installments calculated?
If none of the boxes on lines 4, 5, or 6 is checked, enter 25% of line 3 in each column of line 8.
Can seasonal or uneven income reduce the penalty?
The adjusted seasonal or annualized income installment method may lower one or more required installments. The form says these methods may lower or eliminate the penalty.
Where can I find rates for the penalty calculation?
Use the penalty interest rate for each calendar quarter. SCDOR publishes the rates quarterly in Information Letters at dor.sc.gov/policy.