What IRS Form 1120 (2025) Is For

Form 1120 is the U.S. Corporation Income Tax Return used by domestic C corporations to report income, gains, losses, deductions, and credits to figure their federal income tax liability (IRS Instructions for Form 1120). All domestic corporations must file unless they qualify for a different form or are exempt from filing requirements.

When You’d Use Form 1120 for 2025 (Late or Amended Filing)

You’ll file Form 1120 for 2025 late if you missed the April 15, 2026 deadline (or March 15 for June 30 fiscal years). Amended filings apply when correcting income, deductions, or tax computation errors. Refund claims must be filed within three years of the original due date or two years from tax payment.

Key Rules Specific to 2025

• Late filing penalty: $510 minimum for returns filed over 60 days late.
  
  
• E-filing required: Corporations filing 10+ returns annually must e-file unless exempt.
  
  
• CAMT penalty relief: IRS Notice 2024-66 provides relief for estimated tax under Corporate AMT.
  
  
• Standard rules: NOLs limited to 80% of taxable income, with carryback exceptions for farming and certain insurers.
  
  

Step-by-Step (High Level)

1. Gather transcripts: Request IRS account records with Form 4506-T or through your Business Tax Account.
   
   
2. Complete the form: Use the 2025 Form 1120 with correct schedules.
   
   
3. Attach schedules: Include M-1, M-2, and M-3 if assets exceed $10 million.
   
   
4. File return: E-file if required or mail to the correct IRS center.
   
   
5. Keep copies: Retain returns and documentation for at least three years.
   
   

Common Mistakes and How to Avoid Them

• Missing mandatory e-filing requirements.
  
  
• Miscalculating NOL deductions limited to 80% of taxable income.
  
  
• Leaving M-1/M-2 reconciliations incomplete.
  
  
• Submitting returns without proper corporate officer signatures.
  
  
• Using vague “See Attached” notations instead of required entries.
  
  
• Confusing fiscal deadlines—March 15 for June 30 year-ends vs. April 15 for calendar years.
  
  

What Happens After You File

The IRS processes most returns within 16 weeks, though amended returns often take longer. You’ll receive notices confirming receipt and adjustments if necessary. If you owe, penalties and interest accrue until payment is made. Payment options include Form 9465 installment agreements or online payment plans. If disputes arise, you have formal appeal rights with the IRS.

FAQs

How long do I have to file a late 2025 Form 1120?

There’s no statute of limitations on unfiled returns. The IRS can assess tax indefinitely until you file. However, penalties and interest accumulate each month until the return is submitted. Filing quickly minimizes costs, prevents collection escalation, and starts the statute of limitations clock for future audits or disputes.

What’s the penalty for filing Form 1120 late in 2025?

The IRS charges 5% of unpaid tax per month, up to 25% maximum. If your return is more than 60 days late, the minimum penalty is $510 or the full unpaid tax, whichever is smaller. Interest continues accruing until balances are fully paid. Prompt filing reduces long-term financial impact significantly.

Can I get transcripts for unfiled years?

Yes. You can request wage and income transcripts, account records, and basic entity details even if no return was filed. However, return transcripts are only available for filed returns. Access transcripts through Form 4506-T or your Business Tax Account at IRS.gov to review existing information before submitting overdue filings.

How long do I have to claim a refund for 2025?

Refund claims must be made within three years of the original due date, April 15, 2026, for calendar-year corporations. Alternatively, you have two years from the date you paid the tax, whichever is later. Missing these deadlines forfeits refund eligibility, so timely amended filings are critical when refunds are involved.

Should I also amend my state corporate return?

Yes, in most cases. States typically require amended returns when your federal return changes, particularly if adjustments affect taxable income. Rules vary by jurisdiction, so check your state tax agency’s guidance on deadlines, forms, and penalties. Failing to amend state filings may create mismatched records and trigger state-level audits.

Can I file Form 1120 for 2025 if I never filed the original return?

Yes. You can file your original 2025 Form 1120 at any time, even years late. This is considered an initial delinquent filing, not an amendment requiring Form 1120-X. Filing late will stop additional penalties from accruing, though existing late fees and interest remain. Always file promptly to reduce IRS enforcement actions.

What if I can’t pay the full amount owed?

You should file the return anyway to reduce penalties, then apply for a payment plan. Use Form 9465 or IRS online payment agreements if you owe $50,000 or less. Installment plans prevent immediate levy action and allow structured repayment, though penalties and interest still accrue on the outstanding balance.

‍