IRS Form 8879-CORP: the officer PIN signing process

What the form covers

Form 8879-CORP, E-file Authorization for Corporations, is the form a corporate officer and the electronic return originator (ERO) use when the officer signs the corporation's e-filed return with a personal identification number (PIN). The current revision is Rev. December 2024. It is used with Form 1120, Form 1120-F, Form 1120-H and Form 1120-S, and with any other applicable corporate return filed electronically.

A corporate officer who does not use Form 8879-CORP must use Form 8453-CORP, E-file Declaration for Corporations. Settle which route the officer uses at intake, because the signed document has to be in hand before transmission.

Part I: copy the income line from the right return

The ERO completes Part I from the corporation's return, and zeros may be entered where appropriate. Form 1120 line 11 (total income) goes on Part I line 1, Form 1120-F Section II line 11 goes on line 2, and Form 1120-S line 6 (total income (loss)) goes on line 3. A corporation filing any other return uses line 4 for its form number and the total income from the applicable line.

Failure mode: a 1120-S is keyed with the Form 1120 line 11 figure, or last season's return is used as the source. The officer then signs a total that does not match the return being transmitted. Fix: read the line label on the current return, and compare Part I to that return before the form goes to the officer.

The officer's steps, in order

Step one: confirm the signer. The Form 1120 instructions list the president, vice president, treasurer, assistant treasurer and chief accounting officer. The Form 1120-S instructions add any other corporate officer, such as a tax officer, who is authorized to sign. Check the name and title against the officer record before the form goes out.

Step two: the officer checks one box in Part II. The first box authorizes the ERO firm name to enter the officer's PIN. The second box says the officer will enter the PIN personally as the signature. The officer also verifies the accuracy of the return. The PIN must be five digits and not all zeros.

Step three: the officer signs, dates and writes the title in Part II, then returns the form to the ERO by hand delivery, U.S. mail, private delivery service, email, an Internet website or fax. Keep the signed file and the email it came in.

Step four: the ERO completes Part III with the ERO's six-digit EFIN followed by the ERO's five-digit self-selected PIN, then signs and dates it. The ERO must receive the completed, signed form before the electronic return is transmitted or released for transmission.

Who signs, and where the paid preparer fits

Form 8879-CORP has no paid preparer signature block. Part II is signed by the officer, and Part III is signed by the ERO, identified by EFIN. If the person who prepared the return is also the ERO under the firm's EFIN, that person signs Part III in the ERO role. The preparer's own signature does not stand in for the officer's.

On the Part II authorization line, enter the ERO firm name, not the name of the individual preparing the return, when the ERO is authorized to enter the officer's PIN. The return's own paid preparer rule is separate: the Form 1120 instructions say that generally anyone paid to prepare the return must sign and complete the Paid Preparer Use Only section of the return.

Form 1120 and 1120-S: what changes for 2026

The signing steps are the same on both returns. The differences are the Part I source line and the due date. The dates below apply to tax year 2026 returns filed in 2027. The 2025 returns had earlier dates.

Form 1120-S. The Form 1120-S instructions say an S corporation generally must file by the 15th day of the 3rd month after the end of its tax year. For a calendar-year 2026 return, that is March 15, 2027. The 2025 return was due March 16, 2026, because March 15, 2026 fell on a Sunday.

Form 1120. The Form 1120 instructions say a corporation generally must file by the 15th day of the 4th month after the end of its tax year. For a calendar-year 2026 return, that is April 15, 2027.

Extension. Form 7004 gives an automatic 6-month extension of time to file, and it must generally be filed by the regular due date of the return. A calendar-year 1120-S moves to September 15, 2027, and a calendar-year 1120 moves to October 15, 2027. The officer's signature is still needed before the electronic return is transmitted.

When the officer cannot sign before the deadline

The form makes the signature a gate. The corporation's return will not be transmitted to the IRS until the ERO receives the officer's signed Form 8879-CORP. If the signed form is not in hand on the due date, there is no electronic return to send that day.

Decision rule: if the officer will not have signed by the due date, file Form 7004 by the regular due date and transmit when the signed form arrives. Send the client this before the due date: “We will file a Form 7004 extension for [company name] by [due date] so the return is not late. We cannot transmit the return until [officer name] returns the signed Form 8879-CORP.” Use the same wording each season.

Failure mode: staff enter the officer's PIN from a verbal yes on a phone call. Fix: stop, and ask for the signed form. The form allows ERO entry only where the officer has authorized it in Part II, and a phone call does not create that record.

Failure modes and fixes

Failure: the return is transmitted before the signed form is in the file. Fix: block the transmit step until a signed PDF with the officer's date is attached.

Failure: the form is sent to the IRS because staff think it is the safe copy. Fix: the form says Do not send this form to the IRS unless requested to do so. Keep it on file.

Failure: the return changes after the officer signs. The form says to provide the officer with a corrected copy of Form 8879-CORP if changes are made to the return, for example after the officer's review. Fix: reissue the form, collect a new signature, and keep both versions with a note of which return each covers.

Retention and record-keeping

Keep the completed Form 8879-CORP for 3 years from the later of the return due date or the IRS received date. A calendar-year 2026 Form 1120-S received on time, with a due date of March 15, 2027, is kept through March 15, 2030. If the return is received after its due date, the clock runs from the IRS received date.

Provide the officer with a copy of the signed form on request. The form also refers the ERO to Pub. 4163 for recordkeeping and documentation for business e-file, so keep the signed form, the transmission record and the IRS acknowledgment in one engagement folder.

Wording to send with the form

Send the officer this request with the form: “Please check one box in Part II of the attached Form 8879-CORP, sign and date it, enter your title, and return it to us by [date]. We cannot transmit the corporation's return until we have the signed form.” If the officer chooses to enter the PIN personally, add: “You will enter your PIN yourself at the signature step in our software, using a five-digit PIN that is not all zeros.” Name the screen where that step appears, because an officer who cannot find it will call the firm.