Kewal Krishan & Co, Chartered Accountants
IRS Form 1120

Form 1120, the U.S. Corporation Income Tax Return, is crucial for C corporations to report financial data, income, deductions, and tax obligations to the IRS. It captures comprehensive financial information, including revenue, expenses, assets, liabilities, and tax calculations. Deadlines are usually the 15th day of the 4th month following the tax year close. Corporations might request a six-month extension for filing. Penalties can arise for late filing or tax payment. Completing Form 1120 accurately is vital for tax compliance. Professional guidance is often recommended due to the complexity of tax laws and the potential impact on deductions, credits, and overall tax liability.

Read the following blog for detailed reporting requirements with the IRS and shield your business from IRS penalties!

Filing Obligation:

C Corporations:

C corporations are separate legal entities that are taxed separately from their owners. They are required to file Form 1120 annually with the IRS to report their income, deductions, credits, and calculate their income tax liability.
C corporations are subject to corporate income tax on their taxable income, which is distinct from the income tax obligations of their shareholders.

Entities Treated as Corporations:

Certain entities, such as limited liability companies (LLCs), can elect to be treated as corporations for federal tax purposes. If an LLC or another entity elects to be taxed as a corporation, it must file Form 1120 to report its income and fulfil its tax obligations.

Domestic Corporations:

Domestic corporations, which are incorporated in the United States under state laws, are required to file Form 1120. This includes corporations organized in any U.S. state or territory.

Foreign Corporations Engaged in U.S. Trade or Business:

Certain foreign corporations that conduct business or have operations within the United States are also required to file Form 1120 if they meet specific criteria outlined by the IRS, such as being engaged in a U.S. trade or business.

Taxation of Corporation’s Income:

C corporations are subject to corporate income tax on their profits. Unlike pass-through entities (like S corporations or partnerships), where the income “passes through” to the owners’ personal tax returns, C corporations are taxed separately from their shareholders.

 Who Must File:

The requirement to file IRS Form 1120, the U.S. Corporation Income Tax Return, applies to various entities based on their classification and tax status. Here’s a breakdown of who must file Form 1120:

C Corporations:

C corporations are standalone legal entities that are taxed separately from their owners. They are subject to corporate income tax on their profits. C corporations must file Form 1120 annually to report their income, deductions, credits, and compute their income tax liability.

Domestic Corporations:

Domestic corporations, including those incorporated in the United States under state laws, are generally required to file Form 1120. This includes corporations organized in any U.S. state or territory.

Entities Electing to be Taxed as Corporations:

Certain entities, such as limited liability companies (LLCs), have the option to elect their tax treatment. If an LLC or another entity elects to be treated as a corporation for federal tax purposes, it must file Form 1120 to report its income and fulfil its tax obligations.

Foreign Corporations Engaged in U.S. Business:

Certain foreign corporations conducting business or trade within the United States are required to file Form 1120 if they meet specific criteria outlined by the IRS. This includes foreign corporations engaged in a U.S. trade or business.


Some entities, despite being classified as corporations, might not be required to file Form 1120. For example:

S corporations, which pass through income to shareholders and file Form 1120-S.Partnerships, which file Form 1065.

Sole proprietorships, which report business income on the owner’s individual tax return (Form 1040).

 Income Reporting:

Income reporting on IRS Form 1120 involves detailing various sources of revenue and gains earned by a corporation during the tax year. Here’s a breakdown of income reporting for Form 1120:

Business Revenue:

This includes income generated from the corporation’s primary operations, such as sales of goods or services. It encompasses revenue from regular business activities, including sales of products, services rendered, fees, and other operating income.

Interest Income:

Corporations might earn interest from various sources, such as bank accounts, investments in bonds, loans made to others, or interest-bearing instruments. Interest income received during the tax year should be reported.

Dividend Income:

Dividends received from investments in stocks or certain mutual funds are considered taxable income for the corporation. This includes dividends received from both domestic and foreign corporations.

Capital Gains:

Corporations may realize gains or losses from the sale or exchange of assets, such as stocks, bonds, real estate, or other investments. Both short-term and long-term capital gains or losses should be reported on Form 1120.

Rental Income:

If a corporation owns the property and earns rental income from leasing it out, this income is reportable on Form 1120.

Other Sources:

Miscellaneous sources of income, such as royalties, license fees, patent rights, and other similar sources, should also be reported.

Gross Income Calculation:

The total income earned from these various sources is summed up to calculate the corporation’s gross income.

 Tax Calculation:

Taxable Income Calculation:

Taxable income is calculated by subtracting allowable deductions, credits, and other adjustments from the corporation’s total income. It’s the basis on which income tax is computed.

Tax Rates for Corporations:

Corporations are subject to different tax rates than individuals. While some smaller corporations might be taxed at a flat rate, larger corporations have a progressive tax rate structure. As of my last knowledge update, the federal corporate tax rates ranged from 15% to 35% depending on income levels.

Estimated Tax Payments:

Corporations typically make estimated tax payments throughout the year based on their expected income. Estimated tax payments help corporations avoid penalties for underpayment and ensure a more manageable tax burden at year-end.

Tax Credits and Deductions:

Tax credits directly reduce a corporation’s tax liability. They can include general business credits, investment credits, foreign tax credits, and more.
Deductions reduce the corporation’s taxable income, thereby lowering the amount of income subject to taxation. Various deductions, such as for business expenses, depreciation, and charitable contributions, can help lower the taxable income.

Tax Payments and Refunds:

After calculating the tax liability, corporations make payments to the IRS for the taxes owed. If a corporation has overpaid taxes through estimated payments or qualifies for certain tax credits, it might be entitled to a tax refund.

Tax Year and Accounting Methods:

Corporations must choose a tax year, which can be a calendar year or a fiscal year. They also select an accounting method, either cash or accrual, to report income and expenses.

Tax Payment Schedule:

The tax payment schedule might vary depending on the corporation’s taxable income and other factors. Payment deadlines for estimated taxes and the final tax payment accompany the filing of Form 1120.

Tax Return Signatures and Disclosures:

Form 1120 requires signatures of authorized individuals within the corporation, attesting to the accuracy of the information provided. Disclosures might be necessary for certain tax-related matters or positions taken on the return.

Filing Deadlines:

Calendar Year Corporations:

Most corporations follow a calendar year for tax purposes, meaning their tax year aligns with the calendar year (January 1st to December 31st).
For calendar year corporations, the deadline to file Form 1120 is typically on or around March 15th of the following year. As of my last update, it’s due on the 15th day of the fourth month following the end of the tax year (March 15th for calendar year taxpayers).

Fiscal Year Corporations:

Corporations with fiscal years that don’t follow the calendar year have different filing deadlines. The deadline is generally the 15th day of the fourth month after the end of their fiscal year.

Extension of Time to File:

Corporations can request an extension of time to file Form 1120 by filing Form 7004. This form allows for an automatic six-month extension beyond the original due date.
It’s important to note that an extension to file doesn’t extend the time to pay any taxes owed. Corporations should estimate and pay any taxes due by the original deadline to avoid penalties for late payment.

Estimated Tax Payments:

Corporations are required to make estimated tax payments throughout the year. Failure to make these estimated payments or underpayment can result in penalties, even if the corporation files for an extension.

Penalties for Late Filing:

Failing to file Form 1120 by the deadline can result in penalties imposed by the IRS. These penalties can accrue based on the amount of tax owed and the length of the delay in filing.

Supplemental Forms and Schedules:

Schedule C (Dividends and Special Deductions):

Used to report income or loss from a closely held corporation, deductions not taken elsewhere, and other specific types of income and deductions.

Schedule D (Capital Gains and Losses):

Corporations use this schedule to report gains and losses from the sale or exchange of capital assets, such as stocks, bonds, and property.

Schedule G (Information on Certain Persons Owning the Corporation’s Voting Stock):

Provides information about certain shareholders, including their ownership percentage, to comply with IRS requirements.

Schedule H (Section 280H Limitations for a Personal Service Corporation (PSC)):

If the corporation falls under the category of a Personal Service Corporation (PSC), this schedule helps calculate limitations on deductible expenses related to employee remuneration.

Schedule J (Accumulated Earnings and Profits (E&P)):

Used to figure out the corporation’s accumulated earnings and profits. This schedule is essential for determining dividend distributions and other tax implications.

Schedule K (Other Information):

Includes additional information such as tax-exempt income, deductions, and other items not reported elsewhere.

Form 4626 (Alternative Minimum Tax – Corporations):

If the corporation is subject to the Alternative Minimum Tax (AMT), this form calculates the AMT liability.

Other Forms and Attachments:

Depending on the specific circumstances of the corporation’s operations and transactions, additional forms or attachments might be necessary to provide detailed information required by the IRS.

 Estimated Tax Payments:

Estimated tax payments for corporations, specifically reported on Form 1120, involve several key considerations:

Quarterly Payments: Similar to individual estimated tax payments, corporations filing Form 1120 are required to make estimated tax payments quarterly. These payments are generally due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation’s tax year.
Calculation of Estimated Tax: Corporations estimate their tax liability for the entire tax year and make payments based on this estimation. The estimated tax is typically calculated by considering the expected taxable income, deductions, credits, and other relevant factors.
IRS Form 1120-W: Form 1120-W, often referred to as the Estimated Tax Worksheet, helps corporations calculate the amount of estimated tax to be paid for each quarter. This form assists in estimating tax liability and guides corporations in determining their quarterly payments.
Underpayment Penalties: Failure to make estimated tax payments or underpayment can result in penalties. The IRS imposes penalties for underpayment or late payments of estimated taxes. Corporations should accurately estimate their tax liability to avoid these penalties.
Adjusting Estimated Tax Payments: Corporations can adjust their estimated tax payments during the year if there are changes in income, deductions, or credits. Adjustments help align the payments with the actual tax liability, preventing overpayment or underpayment.
Reporting Estimated Tax Payments on Form 1120: Estimated tax payments made throughout the year are reported on Form 1120, the U.S. Corporation Income Tax Return. These payments are typically recorded in the section dedicated to payments and credits.

Documentation and Record-Keeping: Corporations should maintain accurate records of estimated tax payments, calculations, and supporting documentation. Proper documentation helps in substantiating the accuracy of the payments in case of IRS inquiries or audits.
IRS Electronic Payment Options: Corporations have various electronic payment options available through the Electronic Federal Tax Payment System (EFTPS) or the IRS website to facilitate the submission of estimated tax payments.

Extension vs. Payment Due:
Filing for an extension to file the tax return does not extend the deadline for making estimated tax payments. Even with an extension, corporations are required to make estimated tax payments on time to avoid penalties for underpayment.

Record Keeping:

Financial Statements and Reports:
Corporations should retain financial statements such as balance sheets, income statements, and cash flow statements. These statements provide a comprehensive view of the corporation’s financial health and transactions.

Income and Expenses Documentation:
Maintain detailed records of income sources, including sales receipts, invoices, contracts, and any other documentation related to revenue generation.

Keep records of deductible expenses, such as receipts, invoices, cancelled checks, and bills. These can include operating expenses, employee wages, rent, utilities, supplies, etc.

Asset Records:
Records related to assets should be kept, including purchase documents, depreciation schedules, and records of any sales or disposals of assets during the tax year.

Liabilities and Debt Documentation:
Keep records of loans, mortgages, and other liabilities. This includes loan agreements, repayment schedules, and any interest payments made.

Tax Forms and Filings:
Maintain copies of filed tax returns (including Form 1120), schedules, and any correspondence with the IRS or state tax agencies.

Payroll Records:
Keep records of employee compensation, including payroll records, benefits provided, payroll tax filings, and any employment tax documentation.

Contracts and Agreements:
Documentation related to contracts, agreements, leases, and legal transactions should be retained as they may impact the corporation’s financial status and tax liabilities.

Document Retention Period:

The IRS recommends retaining these records for up to seven years from the date of filing the tax return. However, specific record retention requirements can vary based on certain circumstances, so consulting with a tax professional is advisable.

Digital Record-Keeping:
Digital records are acceptable, but they should be easily accessible and readable. Ensure proper backups and security measures to safeguard electronic records.

Organized Record-Keeping System:
Maintaining a well-organized record-keeping system helps in quick retrieval and review of documentation in case of IRS inquiries or audits.

Accuracy and Completeness:
Records should accurately represent the corporation’s financial activities and transactions. Complete documentation supports the figures reported on Form 1120.

Penalties for Non-Compliance:

Penalties for non-compliance with Form 1120 requirements can occur due to various factors, including failure to file, late filing, inaccuracies, or underpayment of taxes. Here are some common penalties associated with Form 1120:

Failure-to-File Penalty:
Corporations that fail to file Form 1120 by the due date, including extensions if applicable, may face a penalty. The penalty is generally assessed based on the unpaid tax amount. It’s calculated as 5% of the unpaid tax for each month or part of the month the return is late, up to a maximum of 25% of the unpaid tax.

Late Payment Penalty:
If a corporation files its Form 1120 on time but fails to pay the full amount of tax owed by the due date, it may incur a late payment penalty. This penalty is typically 0.5% of the unpaid tax amount for each month or part of the month the tax remains unpaid, up to a maximum of 25% of the unpaid tax.

Underpayment of Estimated Tax Penalty:
Corporations that fail to pay enough estimated tax throughout the year or fail to make timely estimated tax payments may face underpayment penalties. The penalty is calculated based on the underpaid amount and the IRS-established interest rate. Corporations can use Form 2220 to calculate underpayment penalties.

Inaccurate Reporting Penalty:
Corporations that inaccurately report information on Form 1120 may face penalties. If the IRS determines that there’s a substantial understatement of tax, a penalty of 20% of the understated tax amount may be applied.

Negligence or Disregard of Rules Penalty:
Penalties may be imposed if the corporation is found to have shown negligence or disregard of tax rules and regulations. The penalty can be up to 20% of the disallowed portion of the claim for refund or credit.

Fraudulent Activity Penalty:
If the IRS finds that a corporation engaged in fraudulent activities with the intent to evade taxes, the penalty can be severe. It can reach up to 75% of the underpaid tax amount.

Penalty Relief:
In some cases, corporations may qualify for penalty relief if they can show reasonable cause for the non-compliance. The IRS may consider various factors when determining whether to abate or reduce penalties.

How we can help?

Our team simplifies Form 1120 filing, ensuring compliance and maximizing deductions. We offer personalized tax planning, accurate and timely filing, audit support, and continuous updates on tax law changes. Our aim is not just to file taxes but also to empower your financial decisions, providing accessible expertise and ongoing advisory services for your business’s growth.

Have Questions?

Reach Anshul Goyal at for expert guidance and support. Let’s optimize your tax strategy for success. Our COO Anshul Goyal has vast experience on US taxation and International Tax Reporting requirements with the IRS, holding AICPA international tax certifications and has handled complex reporting requirements with the IRS making the US entities compliant on these critical reporting requirements.

Don’t let tax complexities hinder your business growth. Contact us for expert guidance and support in managing your corporate tax responsibilities efficiently. Let’s work together to leverage Singapore’s advantageous tax system to your benefit. Connect with us today!

Disclaimer: Please note that the information provided in this article does not constitute professional advice. The contents are intended for general information purpose only and It’s always recommended to seek counsel from a qualified professional or attorney familiar with your specific business situation before making any decisions.

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