Filing federal business taxes means filling out different forms based on your business structure. The IRS assigns forms by entity type, and missing deadlines or skipping required schedules triggers penalties. C-corporations, partnerships, and S-corps each have their own form and their own set of rules.

This guide covers Form 1120 for corporations and Form 1065 for partnerships. You’ll get the 2026 deadlines, extension rules, and instructions for handling schedules like K-1s and balance sheets. If you’re running a US entity from abroad, there’s a section on remote compliance and EIN setup that deals with the problems non-resident founders actually face.

Introduction to Business Entity Forms (1120 vs. 1065)

The IRS assigns forms by business structure. C-corporations file Form 1120. Partnerships file Form 1065. S-corporations file Form 1120-S. Each one comes with different schedules and different ways to get it wrong.

Sole proprietors report business income on Schedule C of their personal 1040-that’s not what we’re covering here. LLCs can be taxed as sole proprietorships, partnerships, or corporations depending on what they elect. If you don’t make an election, a single-member LLC defaults to Schedule C. Multi-member LLC? That defaults to partnership treatment and you’re filing Form 1065.

When to Use Form 1120 for C-Corps

Form 1120 is the federal income tax return for C-corporations. You incorporated as a regular corporation and didn’t elect S-corp status? You’re filing a 1120. This form reports income, deductions, credits, and calculates corporate tax liability separate from the owners’ personal taxes.

C-corps pay taxes at the entity level. The company pays its own taxes before distributing anything to shareholders. Shareholders receive dividends? They pay taxes again on their personal returns-double taxation. Form 1120 captures the company’s financial activity for the year: gross receipts, cost of goods sold, operating expenses, and special deductions.

The form runs multiple pages and includes several schedules. Schedule C details dividends and special deductions. Schedule J calculates tax owed. Schedule K covers accounting methods and foreign bank accounts. Schedule L shows assets, liabilities, and shareholder equity at the beginning and end of the year. Schedule M-1 reconciles book income with taxable income. Schedule M-2 tracks changes in retained earnings.

Reporting Partnership Income via Form 1065

Partnerships don’t pay federal income tax. They file Form 1065 as an information return that reports income, deductions, gains, and losses, then passes those amounts to individual partners. Each partner gets a Schedule K-1 showing their share of the partnership’s activity, which they report on their own return.

Form 1065 captures the partnership’s finances. Page 1 lists income and deductions. Schedule B asks questions about the partnership’s structure and activities. Schedule K summarizes income and deductions that flow to partners. Schedule L is a balance sheet. Schedule M-1 reconciles book income to reported income, and Schedule M-2 tracks partner capital accounts.

Every partner gets a Schedule K-1, attached to Form 1065 and sent individually. The K-1 breaks out their share of ordinary business income, rental income, interest, dividends, capital gains, and deductions. Partners use these amounts on their 1040s. You’re in multiple partnerships? You get multiple K-1s and report each one separately.

Partnerships with total receipts of $250,000 or more and total assets of $1 million or more must file electronically. More than 100 partners? E-filing is required regardless of receipts or assets. The IRS has tightened e-file mandates over recent years, and 2026 continues that trend.

Step-by-Step Filing Instructions

Forms 1120 and 1065 require attention to detail. You’re reconciling financial records, categorizing expenses, and completing schedules that connect to the main form. Mistakes in one section create errors elsewhere, so work through each line carefully.

Navigating Form 1120 Lines 1-11 (Income and Deductions)

Form 1120 starts with income. Line 1a is gross receipts or sales-total revenue your corporation brought in during the year. Line 1b is returns and allowances, subtracted to get net sales on line 1c. Manufacture or resell products? Line 2 is cost of goods sold, calculated on a separate worksheet. Line 3 subtracts cost of goods sold from net sales to give gross profit.

Lines 4 through 10 cover other income types. Line 4 is dividends from other corporations, domestic and foreign. Schedule C details these dividends and calculates special deductions. Line 5 is interest income. Line 6 is gross rents. Line 7 is gross royalties. Line 8 is capital gain net income, calculated on Schedule D if you sold assets during the year. Line 9 is net gain or loss from Form 4797, used for sales of business property. Line 10 is other income-anything that doesn’t fit the previous categories.

Line 11 is total income, the sum of lines 3 through 10. After line 11 come deductions-compensation of officers, salaries and wages, repairs and maintenance, bad debts, rents, taxes and licenses, interest, charitable contributions, depreciation, depletion, advertising, pension and profit-sharing plans, employee benefit programs, and other deductions. Each deduction has a specific line and most require supporting documentation or worksheets.

The IRS scrutinizes compensation of officers. They want reasonable salaries, not inflated amounts used to reduce taxable income. Your corporation pays you $300,000 but similar companies pay their officers $100,000? Expect questions. Keep records that justify the amount-job duties, hours worked, industry comparisons.

Depreciation goes on line 20 and requires Form 4562 if you’re claiming a deduction for new assets. Section 179 lets you expense up to $1,220,000 of qualifying property in 2026, subject to a phase-out threshold. Bonus depreciation still exists but dropped to 40% for property placed in service in 2026. You can’t depreciate land, inventory, or personal assets-only business property with a useful life longer than one year.

Once you’ve listed all deductions, line 28 gives total deductions. Subtract that from total income to get taxable income on line 30. Schedule J calculates your actual tax liability, including alternative minimum tax if it applies. Credits reduce final tax owed, and you pay the difference or request a refund.

Completing Schedule K-1 and Schedule L for Partnerships

Partnerships must prepare a Schedule K-1 for every partner. The K-1 shows each partner’s distributive share of income, deductions, credits, and other items. The IRS expects a separate K-1 for every partner, whether they’re active or passive, domestic or foreign.

Schedule K on Form 1065 totals everything before breaking it out to individual K-1s. It covers ordinary business income, net rental real estate income, other net rental income, guaranteed payments, interest income, dividends, royalties, net short-term and long-term capital gain, Section 1231 gains, other income and deductions, self-employment earnings, credits, foreign transactions, and alternative minimum tax items. Each line on Schedule K corresponds to a line on each partner’s K-1.

The partnership agreement determines how items are allocated among partners. Agreement says profits and losses split 60/40? Then 60% of each K item goes to one partner and 40% to the other. Some partnerships have special allocations for certain income or expenses, and those must have substantial economic effect under IRS rules. Unusual allocations? Document the business reason and confirm they follow the partnership agreement.

Schedule L lists assets, liabilities, and partners’ capital accounts at the beginning and end of the year. Assets include cash, accounts receivable, inventory, buildings and equipment, land, and other assets. Liabilities include accounts payable, mortgages and notes payable, and other current or long-term liabilities. The difference between assets and liabilities is partners’ capital, broken into capital accounts for each partner.

Capital accounts track each partner’s investment. Start with the balance at the beginning of the year, add contributions and their share of income, subtract distributions and their share of losses, and end with the year-end balance. Schedule M-2 reconciles these capital accounts in detail. Schedule K-1 reports each partner’s capital account information in Part II, including beginning and ending capital, contributions, and distributions during the year.

Schedule M-1 reconciles net income per books with income reported on the return. Differences come from items treated differently for book and tax purposes-meals and entertainment that are only partially deductible, travel and entertainment expenses, depreciation differences, and tax-exempt income. Start with net income from the partnership’s financial statements, add back nondeductible expenses and income recorded on the books but not on the return, subtract tax-exempt income and deductions on the return but not on the books, and arrive at the income reported on line 1 of Form 1065.

Critical 2026 Tax Deadlines and Extensions

Missing a tax deadline costs money. The IRS charges penalties for late filing and late payment, and those penalties compound. Run a business entity? Know your exact due date and whether you qualify for an extension.

March 16, 2026: Deadline for Partnerships and S-Corporations

Partnerships and S-corporations must file by the 15th day of the third month after the end of their tax year. For calendar-year entities, that’s March 15. Since March 15, 2026, falls on a Sunday, the deadline moves to Monday, March 16, 2026.

This applies to Form 1065 for partnerships and Form 1120-S for S-corporations. The earlier deadline exists because partners and shareholders need their K-1s in time to file their own personal returns by April 15. Partnership or S-corp files late? Every partner or shareholder waits for their K-1, and they might file their personal returns on extension just because the entity missed its deadline.

The penalty for late filing is $220 per partner or shareholder per month, up to 12 months. Partnership has 10 partners and files three months late? That’s $6,600 in penalties-$220 times 10 partners times 3 months. Reasonable cause can waive the penalty, but “reasonable cause” has a specific meaning under IRS rules and doesn’t include mistakes or busy schedules.

April 15, 2026: Deadline for C-Corporations

C-corporations filing Form 1120 must file by the 15th day of the fourth month after the end of their tax year. For calendar-year corporations, that’s April 15. In 2026, April 15 falls on a Wednesday, so there’s no weekend extension-the deadline is April 15.

Your corporation uses a fiscal year instead of a calendar year? Your deadline differs. A corporation with a fiscal year ending June 30 files by October 15. Fiscal year ending September 30 means a deadline of January 15. The rule is always the 15th day of the fourth month after year-end.

The penalty for late filing depends on how late you are and how much tax you owe. File more than 60 days late? The minimum penalty is the lesser of $485 or 100% of the tax owed. You owe $300 and file 90 days late? The penalty is $300. Owe $1,000 and file 90 days late? The penalty is $485. On top of that, there’s a separate penalty for late payment-0.5% of unpaid tax per month, up to 25%.

How to Use Form 7004 for a Six-Month Extension

Form 7004 gives you an automatic six-month extension to file your return, but it doesn’t extend the time to pay any tax owed. You must estimate your tax liability and pay it by the original deadline to avoid late-payment penalties. The extension only gives more time to prepare and file the actual return.

Partnerships and S-corps get an extension until September 15 if they file Form 7004 by March 16. C-corporations get an extension until October 15 if they file by April 15. The extension is automatic-you don’t need IRS approval. File the form, pay any estimated tax, and submit your return by the extended deadline.

Form 7004 is one page. Enter your entity name, EIN, address, type of return you’re extending, tax year, and tentative tax liability. Owe money? Include a payment with the form or pay electronically. The IRS processes the extension and updates your account. File your actual return before the extension expires? You’re done. Miss the extended deadline? You face late-filing penalties.

Extensions are common and not a red flag. Many businesses need extra time to finalize their books, gather supporting documents, or coordinate with accountants. The key is filing the extension on time and paying any estimated tax by the original deadline. Do both and you avoid penalties even though your return comes in months later.

Pakistan & NRP Special Considerations

Running a US entity from outside the United States adds complexity that domestic guides usually ignore. You’re dealing with time zones, currency conversions, remote banking, and fiscal year mismatches. The IRS doesn’t offer special forms for non-residents, so you use the same 1120 or 1065 that US-based businesses use, but you need to plan around the practical challenges of distance and jurisdiction.

Remote US Entity Management and Virtual EIN Setup

Incorporating a US business from Pakistan or another country? Your first step is getting an Employer Identification Number (EIN) from the IRS. The EIN is your company’s tax ID, required for opening bank accounts, filing returns, and hiring employees. US residents can apply online and receive an EIN immediately. Non-residents can’t use the online system-they file Form SS-4 by mail or fax, which takes four to six weeks.

Some non-residents use third-party formation services that include EIN application. These services handle the paperwork and correspondence with the IRS, then send you the EIN confirmation letter. Once you have an EIN, you can open a US business bank account. Many banks require in-person visits to open accounts, but a few offer remote account setup for international founders. Mercury, Brex, and Relay are examples of banks that allow non-resident founders to open accounts online, though requirements change frequently.

You’ll also need a registered agent in the state where you incorporate. The registered agent receives legal notices and official correspondence on behalf of your company. This is required by law-you can’t list a foreign address as your registered agent. Many formation services include registered agent service for a yearly fee, typically $100 to $300 per year.

Filing federal business taxes remotely is straightforward once your entity is set up. The IRS doesn’t care where you physically are when you prepare the return, as long as you file on time and report accurately. You can use accounting software like QuickBooks or Xero to track income and expenses throughout the year, then export the data to fill out Form 1120 or 1065. E-filing is required for most entities, and you can e-file from anywhere using approved software.

One practical issue is mail. The IRS still sends certain notices and refunds by US mail, so you need a US mailing address. This can be a registered agent’s address, a virtual mailbox service, or a US-based partner’s address. Virtual mailbox services scan your mail and upload it to an online portal, useful if you’re managing everything remotely and don’t have a US partner who can handle physical mail.

Aligning Overseas Fiscal Calendars with the US Tax Year

Pakistan’s fiscal year runs from July 1 to June 30, which doesn’t match the US calendar year of January 1 to December 31. Managing both a Pakistani business and a US entity? You’re dealing with two tax calendars, two sets of deadlines, and two different reporting periods.

US entities can elect a fiscal year instead of a calendar year, but the IRS has restrictions. C-corporations can choose any fiscal year-end they want, as long as they use it consistently. Partnerships and S-corps generally must use a calendar year unless they meet one of three exceptions: a business purpose for a different year-end, a Section 444 election for a year-end up to three months earlier, or the natural business year test.

Your US entity’s fiscal year matches Pakistan’s July 1 to June 30 cycle? Your US tax return would be due by October 15 each year (the 15th day of the fourth month after June 30). This spreads out your compliance work instead of piling everything into March and April. However, changing your fiscal year after you’ve started filing requires IRS approval, and you need a legitimate business reason-convenience isn’t enough.

For partnerships with international partners, you also need to handle withholding on US-source income. Foreign partner receives income from a US partnership? The partnership must withhold tax under Section 1446 and remit it quarterly. The withholding rate is 37% for non-corporate partners and 21% for corporate partners, applied to the partner’s share of effectively connected income. This is separate from the partnership’s own tax return and requires filing Form 8804 annually and Form 8805 for each foreign partner.

Currency conversion is another practical issue. The IRS requires all amounts in US dollars. Your business transacts in Pakistani rupees? You need to convert those amounts to dollars using the appropriate exchange rate. The IRS accepts any consistently applied exchange rate, but most businesses use the Federal Reserve’s published rates or a similar authoritative source. Document your conversion method and use it consistently year to year.

FAQs and Common Filing Errors