I-338: Composite Return Affidavit (Revision 2023-04)
South Carolina · South Carolina DOR · Used for tax years 2024, 2025, 2026
South Carolina Form I-338 is an affidavit for nonresident participants in a composite tax return. It identifies the participant, entity, and tax year and certifies that the participant has no income taxable to South Carolina other than income from that entity.
Who files this form
The I-338 is for a qualifying participant who wants the entity to use Method A to calculate their tax on a composite return. Without an I-338, the entity must use Method B for that participant.
You may submit this affidavit if you are:
- An individual, trust, or estate that is a nonresident partner, shareholder, or member of a Partnership, S Corporation, or LLC taxed as a Partnership or S Corporation.
- Receiving no income taxable to South Carolina other than income from that entity.
The participant or an agent acting on the participant's behalf should complete and sign the affidavit.
What you'll need
Have the following information ready to complete the affidavit:
- Your name, address, and Social Security Number (SSN) or Federal Identification Number (FEIN). Individual taxpayers must provide their SSN.
- The entity's name, address, and FEIN.
- The type of entity providing the distributed or undistributed South Carolina income.
- The calendar tax year or the beginning and ending dates of your fiscal tax year.
The affidavit also asks for the participant's printed name, a signature, and the date.
How to file
- Complete the affidavit, including the statement that you have no income taxable to South Carolina other than income from the named entity.
- Have the participant or an agent acting on their behalf sign it.
- Submit the completed I-338 directly to the Partnership, S Corporation, or LLC. Do not mail it directly to the South Carolina Department of Revenue (SCDOR).
The entity must provide all I-338 affidavits to the SCDOR with its composite return, Form SC1040, South Carolina Individual Income Tax Return.
Submit a new affidavit to the entity each year. An I-338 is not valid for subsequent years.
Common mistakes
- Mailing the affidavit directly to the SCDOR. Participants should submit it to the entity instead.
- Reusing a prior year's affidavit. The I-338 must be resubmitted to the entity each year.
- Leaving out an individual taxpayer's SSN. Providing it is mandatory.
- Signing an affidavit that is not true, correct, and complete. The affidavit is signed under penalty of perjury. The form warns that willfully making a materially false declaration can result in felony penalties.
Questions people ask
What is a composite return?
A composite return is a single return filed by a Partnership, S Corporation, or qualifying LLC on behalf of two or more nonresident participants. Each participant's tax is calculated separately, then added to determine the total tax due.
What does submitting the I-338 allow the entity to do?
It allows the entity to use either Option 1 or Option 2 under Method A. Option 1 prorates standard or itemized deductions. Option 2 does not use those deductions.
What happens if I do not provide an I-338?
The entity is limited to Method B for your tax calculation. Method B does not allow standard or itemized deductions, and the “safe harbor” is not available for computing active trade or business income.
Can I submit the affidavit if I have other income taxable to South Carolina?
The eligibility rule requires that you have no source of income taxable to South Carolina other than income from the named entity.
Do I need to submit a new affidavit every year?
Yes. The I-338 is not valid for subsequent years and must be resubmitted to the entity each year.