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Estimated Income Tax payments due September 15? Read Information Letter #26-20 first.

Tuesday, Sep 1, 2026

If you’re required to make South Carolina estimated Income Tax payments, make sure you read Information Letter #26-20 to understand how recent legislation impacts your 2026 payments.

Not sure if you are required to make estimated payments? Keep reading to learn more.

What is Information Letter #26-20?

  • The SCDOR published Information Letter #26-20 on Monday to help taxpayers understand the impacts of Act 110 of the 2026 legislative session.  
    • Act 110 amends the state’s Income Tax structure and is effective starting with the 2026 tax year. Tax year 2026 returns aren’t due until April 15, 2027.
  • Information Letter #26-20 offers guidance now for taxpayers making estimated payments, who may need to make adjustments before their September 15 payment.
    • Be sure to take your April 15 and June 15 estimated payments into account when making your September 15 estimated payment.

What has changed? 

Review Information Letter #26-20 for complete details. Changes include:  

  • South Carolina now has two Individual Income Tax brackets, with modified tax rates.
  • South Carolina has decoupled from the federal deductions listed in Internal Revenue Code Sections 63(b) through (g). As a result, the calculation for South Carolina taxable income begins with federal adjusted gross income (AGI) instead of federal taxable income.  
  • South Carolina also has a new South Carolina Income Adjusted Deduction (SCIAD), which replaces the federal standard deduction. The SCIAD is based on a taxpayer’s filing status and may be reduced based on a taxpayer’s federal AGI.
    • See the formula in Information Letter #26-20 for help in determining your SCIAD. The SCDOR also will launch a SCIAD calculator on MyDORWAY later this year.

Should I make estimated payments?

  • You must make estimated payments if you expect to owe an Income Tax liability of $100 or more when filing your South Carolina Individual Income Tax return.

How do I make estimated payments?

  • The easiest way to make your estimated payment is using MyDORWAY, at dor.sc.gov/pay. Select Individual Income Tax Payment to get started.
  • Or, you can make estimated payments using the voucher printed on the SC1040ES.  

What if I haven’t filed my 2025 return?

  • Act 110 does not impact 2025 Income Tax returns, which are due October 15, 2026 after the SCDOR granted an automatic filing extension to all taxpayers in March.  

Stay connected

All SCDOR Advisory Opinions are available at dor.sc.gov/policy. You can have Advisory Opinions delivered straight to your inbox as soon as they’re published by visiting dor.sc.gov/emails and subscribing to the Tax Policy Updates mailing list.

The SCDOR will continue to share information about South Carolina’s new Income Tax structure throughout 2027 tax season. Taxpayers can plan ahead now by visiting dor.sc.gov/iit.

Follow the SCDOR on Instagram, Facebook, X, and YouTube, and subscribe to ReveNews for the latest updates, resources, and reminders.

 

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MEDIA INQUIRES: 

SCDOR Public Information Office 

news@dor.sc.gov

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