C-Corp tax filing doesn’t have to be stressful
Use this checklist to organize corporate income, deductions, balance sheet details, ownership records, tax payments, and required documents before you file.
The deadline to file your C corporation return or request an
extension is APRIL 15, 2027
Section 01
Basic Information
Verify Your Business Filing Type
Ensure your C corporation is properly registered with the IRS for Form 1120 filing. Not sure? Call the IRS Business Help Line: 1-800-829-4933
Employer Identification Number (EIN)
Have your EIN ready. If you don’t have one, apply online at IRS.gov.
State Reporting Details
Compile state and state ID numbers for each location where your business operates or has a tax obligation (nexus).
Organizational Documents
Keep a copy of your articles of incorporation, bylaws, or operating agreement, including amendments.
Previous Tax Returns
Locate and review last year’s federal, state, and local tax returns for reference
Estimated Tax Payments
Record all estimated tax payments made, including amounts and dates for federal, state, and local taxes.
Section 02
Corporation Information
Corporation Details
Collect names, addresses, and SSNs or EINs for all partners active during the tax year
Ownership & Profit Details
List corporate ownership changes, stock issuances, and shareholder details for accurate Form 1120 filing
Financial Activity Reports
Financial activity reports including addresses, compensation, or benefit procedures and tax items
Ownership Changes
Document changes in corporate ownership, stock transfers, and key dates for Form 1120 filing
Section 03
Business and Financial Records
Quarterly Tax Forms
Gather all received forms such as 1099-INT, 1099-MISC, 1099-DIV, 1099-R, and 1099-NEC
Ownership & Profit Details
List corporate earnings, dividends, and payments required for accurate Form 1120 filing
Dividend & Distribution Records
Review dividend statements and distribution records for reportable corporate activity
Credit Certificates
Collect any credit certificates issued by federal or state agencies
Section 04
Documents Received
Accounting Records
Run a P&L report/balance sheet from your accounting software (QuickBooks Online)
Bank and Credit Card Statements
Review statements to validate business expenses and interest payments for Form 1120
Payroll Reports
Copies of issued Forms W-2 and W-3, including 940 and 941/944 returns, plus copies of prior and current payroll taxes paid
Multi-State Activity
For partners in multiple states, compile reports showing sales, payroll, and property values to state
Business Registrations
Record the cost of goods/materials bought for resale or production and the year-end value of inventory
Section 05
Asset Records
Depreciation Schedules
List asset details such as cost, purchase date, prior depreciation, and bonus/section 179 percentage
Log Purchases
Log purchases made during the year, including costs and dates of service
Disposed Assets
Detail sales proceeds, trade-in values, expenses of sale, and accumulated depreciation for assets sold or traded
Vehicle Mileage Log
Provide a mileage log for any business-owned or employee-use vehicles, including parking/tolls/insurance and total mileage
Download Your 1120 C Corporation Checklist Now!
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