Form 1120X (2011): Amended U.S. Corporation Income Tax Return

What Form 1120X Is For

Form 1120X (2011) helps a corporation correct errors on a previously filed Form 1120 or Form 1120-A. Corporations use this amended return to fix income, deductions, credits, or other figures that changed after the original return was filed. The form updates taxable income and any income taxes owed or refunded. If the IRS allows it, this amended form can be used to correct elections missed on the original form. 

When You’d Use Form 1120X

Corporations use Form 1120X (2011) only after the IRS accepts the original income tax return. This amended return is appropriate when a corporation needs to correct errors or update information from a previously filed form. Common situations include:

• Filing the amended return within the IRS timelines:
  
  
  • Three years from the date the original return was considered filed, or
    
    
  • Two years from the date the tax was paid, whichever is later
    
    
• A corporation may need to correct taxable income, deductions, credits, payments, or other items reported on the original form.
  
  
• A corporation may also need to report bad debts or worthless securities, which follow special amendment periods under IRS rules. If the IRS identifies mismatches after your amendment, see how to address an IRS CP2000 discrepancy notice for corporate filings.
  
  
• The amendment process can include claiming carryback years for losses or unused credits when applicable.
• Using a different form when applicable:
  
  • Form 4466 for a quick refund
    
    
  • Form 1139 for a tentative refund
    
    
  • Form 3115 for accounting method changes.
    
    
• You must file a separate Form 1120X for each tax year for which the corporation needs to file an amended return.

Key Rules or Details for the 2011 Tax Year

For the 2011 tax year, corporations filing Form 1120X must follow several specific requirements.

• Paper Filing Only: The 2011 amended return cannot be filed electronically, so the corporation must submit the completed form on paper. This applies even if the original return was filed differently.
• Mailing Location: The form must be mailed to the same IRS Service Center where the corporation originally filed its return. This requirement applies even if the business later changes its address.
• Superseding Return Deadline: Form 1120X should be used only after the deadline for filing a superseding return has passed. This ensures the IRS treats the submission as an amended return rather than a replacement.
• Supporting Documentation: The IRS requires schedules, statements, and explanations supporting each corrected amount on the amended return. All documentation must clearly show how the corrected figures were calculated.
• Disclosure Requirements: Certain corporations are required to attach disclosure forms if the amended tax year includes reportable transactions. These forms help the IRS identify transactions that require additional review.
• Authorized Signature: An officer, such as a president, treasurer, chief accounting officer, or another approved signer, must sign the amended return before mailing. The IRS will not process the return without a valid signature.

Access the IRS Form Help Center for detailed explanations of IRS documents that support amended corporate return filings.

Step-by-Step (High Level)

Use this overview to understand how to complete Form 1120X 2011 for a corporate income tax return:

• Header information: Enter the corporation’s business name, address, employer identification number, and tax year, such as a calendar year filing. Make sure these details match the original tax return and any related information returns.
  
  
• Identifying the return filed: Note which form you are amending, usually Form 1120, and confirm the due date for that year. Certain corporations, including C corporations or controlled group members, should consult the IRS instructions to determine if any special rules apply to the corporation's return.
  
  
• Three-column layout on each page: Use all three columns for each line you are correcting: the original amount, the net change, and the corrected amount. This layout shows the IRS precisely what changed and how it affects the final figures.
  
  
• Explanation and review:  Use Part II to explain each change clearly and reference line numbers. A tax professional can generally help certain corporations gather the necessary supporting documents and complete Form 1120-X correctly before mailing.

Corporations that need to correct missing or outdated filings can review the process outlined in our guide to unfiled federal returns.

Common Mistakes and How to Avoid Them

When completing Form 1120X 2011, several issues can delay processing or lead to IRS questions. Keep these points in mind:

• Filing too early: Do not file an amended return until the IRS has processed the original filing. Submitting it too soon can cause delays or create conflicting information in your account.
• Incomplete explanations: Part II must clearly illustrate what changed, why it changed, and how you calculated the corrected amount. Missing or vague explanations can slow down IRS review.
  
  
• Missing supporting documents: Attach all relevant schedules, statements, and forms that support the corrected figures. The IRS uses these documents to verify the accuracy of each change.
  
  
• Not updating related items: When taxable income or deductions change, review and update any affected credits or limits. This keeps the amended return consistent and prevents mismatches.
  
  
• Missing the filing window:  Determine the applicable three-year or two-year deadlines before filing. These time limits determine whether the IRS can accept the amended return.
  
  
• Using the wrong form: Use Form 4466 for a quick refund, Form 1139 for a tentative refund, or Form 3115 for changes to your accounting method. Selecting the correct form ensures that your request is processed correctly.

What Happens After You File

After you file Form 1120X (2011), the IRS reviews the corporation’s return and compares it with the original tax return. Processing takes time because paper forms must be checked against information returns and supporting documents. The IRS may request additional details if any information on the amended page requires clarification. 

Interest continues to accrue on any outstanding balance, even if the corporation has made estimated tax payments. A tax professional can help certain corporations, including C corporations or controlled group members, understand how updates to prior years allowed may affect total assets and the return filed.

FAQs

Can a corporate income tax return for 2011 be filed electronically when using Form 1120X?

Form 1120X (2011) cannot be filed electronically. The amended return must be printed, signed, and mailed to the correct IRS Service Center.

Do I need a separate amended return for each prior year if I discover errors in more than one tax year?

Yes, the IRS requires a separate Form 1120X for each tax year. Corporations cannot combine multiple amended returns into one filing.

Can a corporation amend Form 1120 more than once if new information appears later?

Yes, a corporation may file another Form 1120X for the same tax year as long as the filing window is still open under IRS rules.

Does filing an amended return increase the chance of an examination of the corporate returns?

Not automatically, the IRS reviews each amendment, but filing Form 1120X does not guarantee an examination.

How do carryback claims work when amending prior years with Form 1120X?

Carryback years follow special rules. When a corporation carries back a loss or credit from a later year within the allowed timeframe, it can amend its return for the earlier year.