IRS Form 8879-S – IRS e-file Signature Authorization for Form 1120-S

IRS Form 8879-S – In today’s digital age, e-filing tax returns has become the norm for businesses seeking efficiency and accuracy. For S corporations, IRS Form 8879-S plays a crucial role in this process. This form, officially known as the IRS e-file Signature Authorization for Form 1120-S, allows corporate officers to electronically sign their income tax returns using a personal identification number (PIN). Whether you’re a business owner, tax preparer, or electronic return originator (ERO), understanding Form 8879-S is essential for seamless compliance with IRS requirements.

This article provides an in-depth, SEO-optimized overview of Form 8879-S, including its purpose, how to complete it, filing guidelines, and key deadlines for tax year 2025. We’ll draw from official IRS sources to ensure accuracy and reliability.

What Is IRS Form 8879-S?

IRS Form 8879-S is a declaration and authorization document used specifically for e-filing Form 1120-S, the U.S. Income Tax Return for an S Corporation. It enables a corporate officer to authorize an ERO—such as a tax professional or software provider—to submit the return electronically on their behalf. Instead of a traditional wet signature, the form uses a PIN as the electronic signature, streamlining the process while maintaining security.

The form also allows for consent to electronic funds withdrawal if the S corporation owes taxes. This makes it a vital tool for S corporations opting for paperless filing, which is faster and reduces errors compared to mailing physical forms.

Key Features of Form 8879-S

  • Revision Date: The current version is available via the IRS website, with no recent developments reported as of January 29, 2026.
  • OMB Number: 1545-0123.
  • Related Forms: Often used alongside Form 1120-S. An alternative is Form 8453-S for declarations without a PIN.
  • Download Link: You can download the latest PDF version of Form 8879-S directly from the IRS at https://www.irs.gov/pub/irs-pdf/f8879s.pdf.

Who Needs to Use Form 8879-S?

This form is designed for:

  • Corporate Officers: Any authorized officer of an S corporation who wants to e-file Form 1120-S using a PIN.
  • Electronic Return Originators (EROs): Tax professionals or authorized e-file providers who prepare and transmit the return.

If your S corporation elects not to use a PIN for electronic signing, you must instead use Form 8453-S, the S Corporation Income Tax Declaration for an IRS e-file Return. Form 8879-S is not required for paper filings but is mandatory for PIN-based e-filing.

S corporations benefit from this form if they aim to:

  • Avoid mailing delays.
  • Receive faster acknowledgments from the IRS.
  • Simplify payment of any owed taxes via direct debit.

When to Use Form 8879-S: Purpose and Benefits?

The primary purpose of Form 8879-S is to authorize the electronic submission of Form 1120-S and verify the accuracy of the return information. It should be used when:

  • The corporate officer authorizes the ERO to enter or generate their PIN.
  • The return includes consent for electronic funds withdrawal for tax payments.

Benefits of E-Filing with Form 8879-S

  • Speed: E-filed returns are processed faster, often with quicker refunds or confirmations.
  • Security: PINs provide a secure alternative to physical signatures.
  • Convenience: No need to print, sign, or mail documents.
  • Accuracy: Reduces errors associated with manual entry.
  • Compliance: Aligns with IRS encouragement for electronic filing, as outlined in Publication 4163, Modernized e-File (MeF) Information for Authorized IRS e-file Providers for Business Returns.

For tax year 2025, using Form 8879-S ensures your S corporation stays compliant while leveraging modern tax technology.

How to Complete IRS Form 8879-S: Step-by-Step Guide?

Completing Form 8879-S is straightforward but requires careful review to avoid mistakes. The form is divided into three parts, based on the structure from official IRS documentation.

Part I: Tax Return Information (Whole Dollars Only)

Enter key figures from your Form 1120-S:

  1. Gross receipts or sales less returns and allowances (line 1c).
  2. Gross profit (line 3).
  3. Ordinary business income (loss) (line 21).
  4. Net rental real estate income (loss) (Schedule K, line 2).
  5. Income (loss) reconciliation (Schedule K, line 18).

Zeros can be entered where appropriate.

Part II: Declaration and Signature Authorization of Officer

  • The officer declares under penalties of perjury that they’ve examined the return and it’s accurate.
  • Consent is given for the ERO to transmit the return and receive IRS acknowledgments.
  • If applicable, authorize electronic funds withdrawal, including account details from tax software.
  • Officer’s PIN: Check the box if authorizing the ERO to enter the PIN or if entering it yourself. Enter a five-digit PIN (not all zeros).
  • Sign and date, including the officer’s title.

Part III: Certification and Authentication

  • ERO enters their Electronic Filer Identification Number (EFIN) followed by a five-digit self-selected PIN.
  • The ERO certifies compliance with IRS e-file rules, referencing Publications 3112 and 4163.
  • ERO signs and dates.

Officer and ERO Responsibilities

  • Officer: Review all amounts, select a PIN, and keep a copy of the return.
  • ERO: Enter corporation details, provide the form to the officer for review (via mail, email, or fax), retain the completed form for at least three years, and do not submit it to the IRS unless requested.

Always use tax preparation software to generate the form accurately.

Filing Guidelines and Deadlines for Tax Year 2025

Form 8879-S itself is not filed with the IRS—it’s retained by the ERO. The associated Form 1120-S must be e-filed by the due date.

For tax year 2025:

  • Calendar Year S Corporations: Due date is March 16, 2026 (since March 15 falls on a Sunday).
  • Fiscal Year Corporations: 15th day of the 3rd month after the tax year ends.
  • Extensions: File Form 7004 for a six-month extension, but any taxes owed must be paid by the original due date.

If your S corporation has dissolved, file by the 15th day of the 3rd month after dissolution.

Common Mistakes to Avoid When Using Form 8879-S

To ensure smooth e-filing:

  • Double-Check Amounts: Mismatches in Part I can lead to rejections.
  • PIN Errors: Avoid all zeros; choose a secure, memorable PIN.
  • Incomplete Reviews: Always examine the full return before signing.
  • Submission Mishaps: Do not send Form 8879-S to the IRS—it’s for ERO records only.
  • Missed Deadlines: Late filings can result in penalties.

Consulting a tax professional can help mitigate these issues.

Conclusion

IRS Form 8879-S simplifies e-filing for S corporations, making tax compliance more efficient and secure. By using this form for your Form 1120-S submission, you can avoid paper hassles and focus on growing your business. For the most up-to-date version, download the PDF from the IRS website: https://www.irs.gov/pub/irs-pdf/f8879s.pdf.

If you have questions about your specific situation, refer to IRS Publication 4163 or consult a qualified tax advisor. Staying informed about forms like 8879-S ensures your S corporation remains in good standing with the IRS.