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IRSCorporate Tax (1120 Series)

Official form guide

Form 1120C: 1120-C

Form 1120-C is the U.S. corporate income tax return for personal service corporations (PSCs). File it to report taxable income, calculate tax, and claim credits for a PSC.

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Form Overview

IRS Form 1120C - 1120-C

Form 1120-C is the U.S. corporate income tax return for personal service corporations (PSCs). File it to report taxable income, calculate tax, and claim credits for a PSC.

The form captures gross receipts, deductible expenses, PSC‑specific tax adjustments, tax credits, and the calculated corporate tax liability.

Risk Radar

Scan points
  • 1A single missing PSC adjustment can double the tax due.
  • 2Missing PSC‑specific adjustments (e.g., personal service income allocation)
  • 3Incorrect tax rate applied
  • 4Failure to attach{required} Schedule K
  • 5Signature omitted or dated incorrectly

Plain English

If your corporation mainly provides personal services—like law, accounting, consulting, or health care—and meets the IRS definition of a personal service corporation, you must file this return. It works like the regular corporate tax form but uses special rules for PSCs.

Submission Date

  • Filing date: 2026-01-20 12:10:34
  • Preparation window: collect IDs, supporting records, and signatures in advance.
  • Final review: verify names, dates, and required fields before submission.

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Glossary Terms

income taxliabilityincomehealthgross

Hover a term to preview the meaning.

What this form is for

  • Use when the corporation meets the IRS definition of a personal service corporation.
  • Do not use for regular C‑corporations that are not PSCs.
  • Check Form 1120 if the corporation does not qualify as a PSC.

Form selector

Use this form or another form?

Corporation not a PSC

Regular corporate tax rules apply

✓ Confirm PSC status before filing

Form 1120

Non‑profit corporation

Different filing purpose

✓ Verify tax‑exempt status first

Form 990

Small business with gross receipts < $250,000

S‑corporation election required

✓ Ensure S‑corp election is in place

Form 1120‑S

Deadline or filing window

Form 1120-C is due by the 15th day of the fourth month after the tax year ends. If the due date falls on a weekend or holiday, the deadline moves to the next business day. Extensions can be requested with Form 7004, extending the filing deadline by six months, but any tax due must still be paid by the original due date to avoid interest.

  • —Taxable income | Apply 21% rate | Tax liability | Verify PSC adjustments first

Checklist

What you need before filling it out

1

Gross receipts

Sales invoices, service contracts · Income statement

⚠ Often omitted small contracts✕ Medium
2

Deductible expenses

Receipts, payroll records · Expense schedule

⚠ Mis‑classifying personal expenses✕ High
3

PSC adjustment

Allocation worksheet · Schedule K

⚠ Forgetting to allocate personal service income✕ High
4

Tax credit claims

Credit documentation (e.g., R&D) · Credit worksheets

⚠ Missing supporting forms✕ Medium
5

Signature

Authorized officer ID · Signature block

⚠ Blank or unsigned✕ Critical
6

EIN

IRS notice of EIN · Header of return

⚠ Wrong EIN leads to processing delay✕ High

Before you submit

  1. 1Use the 2024 edition of Form 1120-C
  2. 2Confirm corporation qualifies as a PSC
  3. 3Complete all required schedules (K, L, M‑1, etc.)
  4. 4Verify arithmetic and totals with a calculator
  5. 5Attach all supporting documents
  6. 6Sign and date the return
  7. 7Enter correct EIN and corporate name
  8. 8Select the correct filing method (paper or MeF)
  9. 9If mailing, use the address from the 2024 instructions
  10. 10If e‑filing, ensure the corporate PIN is active
  11. 11Retain a copy of the filed return for records
  12. 12Check for any IRS notices after filing

How to file this form

  1. 1Gather year‑end financial statements and supporting documents
  2. 2Download the 2024 Form 1120‑C and instructions from IRS.gov
  3. 3Complete the form line‑by‑line, applying PSC adjustments
  4. 4Run a final arithmetic check and sign the return
  5. 5If e‑filing, upload via the MeF portal; if paper, mail to the Service Center address
  6. 6Keep the delivery receipt or e‑file confirmation
  7. 7Monitor for IRS acknowledgment or any follow‑up notices

Known limitations

  1. 1Instructions may reference tax law changes after the form’s edition date
  2. 2Electronic filing requires prior IRS authorization
  3. 3The form does not calculate state corporate taxes
  4. 4Schedule K details are not fully explained in the brief source
  5. 5Penalty calculations are not provided on the form itself

Field map

Compact field-by-field guide

9 fields

Entity Info

2 items

Corporation Name and EIN

Full legal name of the corporation and its Employer Identification Number.

Requiredtext
Address and Date Incorporated

Current mailing address and date of incorporation.

Requiredtext

Income

3 items

Gross Receipts or Sales

Total revenue from business operations before deducting costs.

Requiredamount
Cost of Goods Sold

Direct costs attributable to producing goods sold by the corporation.

amount
Total Income

Gross receipts minus cost of goods sold and returns/allowances.

Requiredamount

Deductions

1 items

Total Deductions

Sum of all business expenses including compensation, rent, interest, taxes, and depreciation.

Requiredamount

Tax

2 items

Taxable Income

Total income minus total deductions.

Requiredamount
Total Tax

Tax calculated on taxable income using the applicable corporate tax rate, minus any credits.

Requiredamount

Signatures

1 items

Officer Signature

An authorized corporate officer must sign and date the return.

Requiredsignature
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Current form status
IRS

The latest version of Form 1120-C is the 2024 edition, released October 2023. Verify the edition date on the form before use.

What changed or needs a fresh check

  • Edition date – confirm the form shows 2024 edition
  • Fee – no filing fee for Form 1120-C
  • Mailing address – use the address in the 2024 instructions for paper filing
  • Electronic filing eligibility – verify the corporation’s e‑file PIN is active
  • Signature line – ensure the authorized officer signs and dates
  • EIN – double‑check the EIN matches the corporation’s records

Form Preview

Form 1120C page 1

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Form 1120C page 2

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Quick Facts

Personal service corporations (PSC) that are domestic U.S. corporations file Form 1120-C.
The form captures gross receipts, deductible expenses, PSC‑specific tax adjustments, tax credits, and the calculated corporate tax liability.
Form 1120-C is due the 15th day of the fourth month after the corporation’s tax year ends (generally April 15 for calendar‑year filers).
Submit the completed form to the IRS Service Center listed in the instructions, either by mail or electronically through the Modernized e‑File (MeF) system if the corporation is authorized.
Errors can trigger penalties, interest, or a delayed refund, and may cause the IRS to reclassify the corporation, affecting tax rates.
Gather year‑end financial statements, calculate ordinary business income, apply PSC adjustments, compute tax using the 21% corporate rate, complete the form line‑by‑line, and attach required schedules. Review the form for arithmetic accuracy, sign, and file by the deadline either electronically or by mail.

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After you file

  1. 1Save the signed copy and all attachments in the corporate records
  2. 2Record the filing date and confirmation number (mail receipt or e‑file ID)
  3. 3Track payment of any tax due to avoid interest
  4. 4Monitor the corporation’s IRS account for acceptance or notices
  5. 5Respond promptly to any IRS correspondence
  6. 6Update the corporate tax calendar for next year’s deadline
  7. 7Retain the return for at least seven years as required

Sources

  • SRCForm 1120‑C official title and purposeIRS
  • SRCPSC definitionIRS instructions for Form 1120‑C
  • SRCFiling deadlineIRS Publication 542
  • SRCElectronic filing eligibilityIRS MeF guidelines
  • SRCNo filing feeIRS fee schedule
  • SRCExtension rulesForm 7004 instructions
  • SRCSchedule K requirementForm 1120‑C instructions
  • SRCSignature requirementForm 1120‑C line‑1
  • SRCEdition dateIRS form release notes
  • SRCMailing addressIRS 2024 Form 1120‑C instructions

Common confusion points

PSC definition

Overlaps with professional corporations

→ Verify IRS definition in instructions

Tax rate applied

Some think PSCs have a special rate

→ Use the standard 21% corporate rate

Schedule K requirement

Not all filers realize it’s mandatory for PSCs

→ Check the schedule list in the instructions

Electronic vs. paper filing

Eligibility rules differ

→ Confirm MeF authorization before choosing

Extension filing

Form 7004 is for many corporations but not all

→ Verify extension eligibility for PSCs

Workflow map

Related forms and next steps

7 signals

Before

Form SS‑4 – Obtain EIN

Current

1120C

After

Form 1120‑C – File returnForm 941 – Report payroll taxes

Often used with

Schedule K – PSC adjustmentsForm 7004 – Request extension

⚠ If something goes wrong

  • Form 2210 – Compute interest & penalties
  • Form 8865 – Report foreign partnerships (if applicable)

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Copyright & Licensing - US Government Forms

Independent guide

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Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
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