How to Fill Out IRS Form 1120: U.S. Corporation Income Tax Return

To fill out IRS Form 1120, a domestic C corporation reports its gross income on page 1, subtracts its deductions to arrive at taxable income, applies the flat 21 percent corporate rate, subtracts credits and estimated payments already made, and attaches the schedules the IRS requires for its size and situation.1Internal Revenue Service. About Form 1120, U.S. Corporation Income Tax Return2Office of the Law Revision Counsel. 26 U.S. Code 11 – Tax Imposed The return is due by the 15th day of the fourth month after the tax year ends, and the obligation applies whether the corporation made money, broke even, or lost money.

Who Has to File

Every domestic corporation subject to income tax files a return, including corporations organized under state law, LLCs and other eligible entities that elected corporate treatment under the check-the-box rules, and foreign entities treated as domestic corporations for tax purposes.3Office of the Law Revision Counsel. 26 U.S.C. 6012 – Persons Required to Make Returns of Income4eCFR. 26 CFR 301.7701-3 – Classification of Certain Business Entities An inactive corporation that earned nothing still owes a zero return.

One important boundary: a corporation with a valid S election files Form 1120-S instead, not Form 1120. If you aren’t sure which election is in place, check the entity’s IRS determination letter or its last filed return before you start.

What to Gather Before You Start

Have the following in front of you:

  • The corporation’s Employer Identification Number.
  • The accounting method (cash or accrual) and the tax year (calendar or fiscal).
  • Full financial statements: gross receipts, cost of goods sold, operating expenses, officer compensation, interest and rental income, and any other income for the year.
  • Year-end balance sheet figures for Schedule L, unless total receipts and total assets are both under $250,000.5Internal Revenue Service. Instructions for Form 1120 – Section: Schedule L. Balance Sheets per Books
  • Depreciation records for Form 4562, which feeds line 20.6Internal Revenue Service. About Form 4562, Depreciation and Amortization
  • Officer compensation details for Form 1125-E if total receipts are $500,000 or more, including each officer’s name, Social Security number, time devoted to the business, and pay.7Internal Revenue Service. About Form 1125-E, Compensation of Officers
  • Inventory records for Form 1125-A if the corporation produces or sells merchandise, including beginning and ending inventory, materials, and labor.8Internal Revenue Service. Form 1125-A – Cost of Goods Sold

Download the current-year Form 1120 and its instructions from irs.gov. Working from an outdated version is one of the easiest ways to make an avoidable mistake.

Page 1: Reporting Income

The top half of page 1 builds total income line by line.9Internal Revenue Service. Instructions for Form 1120 – Section: Line 1. Gross Receipts or Sales

  • Line 1a: gross receipts or sales. Subtract returns and allowances on line 1b to reach net receipts on line 1c.
  • Line 2: cost of goods sold, carried from line 8 of Form 1125-A.
  • Line 3: gross profit (line 1c minus line 2).
  • Line 4: dividends and inclusions, from Schedule C, which also calculates the dividends-received deduction if the corporation owns stock in other companies.
  • Lines 5 through 10: interest income, gross rents, gross royalties, capital gains from Schedule D, net gain or loss from Form 4797, and other income. Report interest income gross; do not net it against interest expense.
  • Line 11: total income, adding lines 3 through 10.

Page 1: Deductions and the Tax

Lines 12 through 29 are where deductions go, and every one of them needs documentation the IRS can inspect later.

  • Line 12: officer compensation. Attach Form 1125-E when receipts hit $500,000 or more.7Internal Revenue Service. About Form 1125-E, Compensation of Officers
  • Line 13: salaries and wages for everyone else.
  • Lines 14 and 15: repairs and maintenance, and bad debts that became worthless during the year.
  • Lines 16 through 18: rents, state and local taxes and licenses, and business interest. Business interest may be capped under Section 163(j), which requires Form 8990.
  • Line 19: charitable contributions, deductible up to 10 percent of taxable income figured before the contribution deduction itself and before any net operating loss or capital loss carryback; excess contributions carry forward up to five years.10Office of the Law Revision Counsel. 26 U.S. Code 170 – Charitable, Etc., Contributions and Gifts
  • Line 20: depreciation from Form 4562, including any Section 179 expensing and bonus depreciation.6Internal Revenue Service. About Form 4562, Depreciation and Amortization
  • Line 29: total deductions.

Line 30 gives taxable income (before special deductions on line 29b, including any net operating loss and the dividends-received deduction). Line 31 applies the flat 21 percent rate.2Office of the Law Revision Counsel. 26 U.S. Code 11 – Tax Imposed Credits from Schedule J reduce the tax, and estimated payments already made during the year are subtracted to produce the balance due or overpayment.

The Schedules You Attach

Form 1120 travels with several schedules. Which ones you owe depends mostly on the corporation’s size.

Schedule K

Schedule K captures the corporation’s structural information: accounting method, principal business activity code, controlled-group status, foreign ownership, and stock ownership. Question 13 matters especially. Answering “Yes” (both total receipts and total assets under $250,000) exempts the corporation from Schedules L, M-1, and M-2.5Internal Revenue Service. Instructions for Form 1120 – Section: Schedule L. Balance Sheets per Books

Schedule L

Schedule L is the balance sheet: assets, liabilities, and shareholders’ equity at the beginning and end of the year. Figures should tie to the corporation’s books.

Schedules M-1, M-2, and M-3

Schedule M-1 reconciles book income to taxable income, since the two rarely match. Typical differences include fines and penalties (deductible on the books but not on the return), officers’ life insurance premiums, tax-exempt interest, and depreciation calculated on different methods. Corporations with total assets of $10 million or more skip M-1 and file the more detailed Schedule M-3.11Internal Revenue Service. Instructions for Schedule M-3 (Form 1120) Schedule M-2 tracks changes in unappropriated retained earnings.

Foreign Ownership: Form 5472

If any foreign shareholder owns 25 percent or more of the voting stock or total value, the corporation must file a separate Form 5472 for each such owner it had reportable transactions with during the year, including payments for services, rents, loans, and asset purchases.12Internal Revenue Service. About Form 5472, Information Return of a 25% Foreign-Owned U.S. Corporation The penalty for missing a required 5472 is $25,000 per form, with additional $25,000 penalties for each 30-day period the failure continues after the IRS notifies you. Foreign-owned single-member LLCs treated as disregarded entities have the same obligation even though they don’t otherwise file a corporate return.

When It’s Due and How to Get More Time

The return is due by the 15th day of the fourth month after the tax year ends. For calendar-year filers that’s April 15. Corporations with a fiscal year ending June 30 file by September 15, the 15th day of the third month.13Internal Revenue Service. Starting or Ending a Business 3 When the deadline lands on a weekend or legal holiday, it moves to the next business day.14Internal Revenue Service. When to File

Filing Form 7004 by the original due date buys an automatic six-month extension for the paperwork.15Internal Revenue Service. About Form 7004, Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns Any tax owed is still due on the original date. Interest runs on unpaid balances from that date at a rate the IRS updates quarterly.16Internal Revenue Service. Interest The extension does protect you from the much larger failure-to-file penalty.

How to File and Pay

Most corporations e-file through the IRS Modernized e-File system, either directly with approved software or through an authorized e-file provider.17Internal Revenue Service. Modernized e-File (MeF) Internet Filing E-filing is mandatory for corporations that have $10 million or more in assets and file at least 250 returns a year.18Internal Revenue Service. E-File for Large Business and International (LB&I) Below that threshold, e-filing is still faster and produces an electronic acknowledgment.

If you file on paper, the correct mailing address depends on your principal place of business and total assets; the current list is on the IRS “Where to File Your Taxes (for Forms 1120)” page.19Internal Revenue Service. Where to File Your Taxes (for Forms 1120) Send paper returns by certified mail with a return receipt to prove the filing date. Pay any balance through the Electronic Federal Tax Payment System, which is free and returns immediate confirmation.20Internal Revenue Service. EFTPS: The Electronic Federal Tax Payment System Enrollment at eftps.gov takes roughly a week, so set it up well before you need to pay.

Estimated Tax During the Year

A corporation that expects to owe $500 or more when the return is filed must pay estimated tax in four installments during the year.21Internal Revenue Service. Estimated Taxes For calendar-year corporations, the installments are due April 15, June 15, September 15, and December 15, generally 25 percent of the year’s expected tax each.22Office of the Law Revision Counsel. 26 U.S. Code 6655 – Failure by Corporation to Pay Estimated Income Tax The safe harbor is 100 percent of the current year’s liability or 100 percent of the prior year’s (if that year was a full 12 months and showed a liability). Large corporations, generally those with $1 million or more in taxable income in any of the three prior years, can only use the prior-year figure for the first installment.

Penalties if You File or Pay Late

The failure-to-file penalty is 5 percent of the unpaid tax for each month or part of a month the return is late, capped at 25 percent.23Internal Revenue Service. Failure to File Penalty The failure-to-pay penalty is 0.5 percent per month. That gap is the reason to file on time, or file Form 7004, even when you can’t pay the balance in full. When both penalties apply in the same month, the failure-to-file penalty is reduced by the failure-to-pay penalty, so they don’t fully stack. Interest compounds daily on any unpaid balance from the original due date.24Office of the Law Revision Counsel. 26 U.S. Code 6601 – Interest on Underpayment, Nonpayment, or Extensions of Time for Payment, of Tax

How Long to Keep the Records

Keep records for at least three years from the date the return was filed.25Internal Revenue Service. How Long Should I Keep Records Two situations stretch that window: six years if the corporation omitted more than 25 percent of its gross income, and seven years if the return claimed a deduction for bad debts or worthless securities.26Internal Revenue Service. Topic No. 305, Recordkeeping Holding everything for seven years is the safe default. Store the filed return with every supporting schedule, W-2 and 1099, bank statement, and receipt behind each deduction.