What Is Form 1120-S?
Form 1120-S is the U.S. Income Tax Return that S Corporations must file with the IRS each year. It reports the business’s income, deductions, and credits but does not calculate taxes for the company itself. Instead, S Corporations are pass-through entities, meaning profits and losses pass to the owners (shareholders), who report them on their personal tax returns. Filing this form helps S Corporations follow tax laws and gives shareholders the details they need for their own tax filings.
Who Can File Form 1120-S?
A business must elect to be an S Corporation by filing Form 2553 with the IRS before filing Form 1120-S. If this step hasn’t been completed, the business may need to file a regular corporate tax return (Form 1120) instead.
When Is Form 1120-S Due?
Form 1120-S is due on the 15th day of the third month after the end of the tax year. For S Corporations using a calendar year (January–December), the deadline for the 2024 tax year is March 17, 2025, because March 15 falls on a weekend.
If the due date falls on a weekend or holiday, it moves to the next business day. You can request a six-month extension by filing Form 7004 before the deadline, but any taxes owed must still be paid on time.
Form 1120 vs. 1120-S: Key Differences
Form 1120 and Form 1120-S are both IRS tax forms for corporations, but they are used for different business types and have key tax differences.
| Feature | Form 1120 (C Corporation) | Form 1120-S (S Corporation) |
|---|---|---|
| Who Files? | C Corporations | S Corporations |
| Tax Treatment | Pays corporate tax; profits may be taxed again as dividends (double taxation) | Profits pass through to shareholders and are taxed on personal returns |
| Shareholder Limit | No limit | Maximum of 100 shareholders |
| Stock Classes | Multiple classes allowed | Only one class of stock allowed |
| Ownership Restrictions | Open to individuals, corporations, and foreign entities | Only U.S. individuals (no corporations or partnerships) |
| Filing Requirement | No election needed | Must file Form 2553 to elect S Corp status |
How to Fill Out Form 1120-S
Filing Form 1120-S might seem complicated, but breaking it down into simple steps can make the process easier. This form reports an S Corporation’s income, deductions, and credits to the IRS. Follow these steps to complete it correctly:
1. Enter Basic Business Information
Begin by entering details about your corporation. You’ll need your business name, address, and Employer Identification Number (EIN). If this is your first year as an S Corporation, make sure you’ve filed Form 2553 or attach it now. You’ll also enter the date your business was incorporated and your total assets at the end of the tax year.
If you haven’t applied for an EIN yet, you can file Form SS-4 to get your EIN.
2. Report Your Business Income
Next, you’ll fill out the Income section. Enter your total revenue (gross receipts or sales) and subtract any returns or allowances. If your business sells products, include the cost of goods sold. There’s also a space for other types of income, like rental earnings or capital gains. Once you’ve entered everything, add up the numbers to get your total income.
3. List Business Expenses and Deductions
Now, it’s time to report what your business spent. You’ll include costs like employee salaries, rent, utilities, taxes, and insurance. If you’ve purchased business assets, you may also need to report depreciation. Don’t forget to include advertising expenses and employee benefits. Once all deductions are listed, subtract them from your total income—this gives you your ordinary business income (or loss).
4. Calculate Taxes and Payments
If your business owes any special taxes (like those on capital gains), you’ll enter them in this section. You’ll also record any estimated tax payments made during the year. After this, you’ll see whether you owe money or if you overpaid and qualify for a refund.
5. Sign, Attach Any Required Forms, and File
Before submitting, an officer of the corporation must sign the form. You may also need to attach additional schedules, like Schedule K-1, which shows how profits and losses are divided among shareholders. Once everything is in place, file your Form 1120-S before the deadline to stay compliant.
Penalties for Late Filing
Filing Form 1120-S late costs $245 per shareholder, per month (up to 12 months). If tax is owed, add 5% per month (up to 25%), with a minimum penalty of $510 if over 60 days late. Filing Form 7004 can help avoid penalties.
Other Forms You May Need
When filing Form 1120-S, attaching the right supporting forms and schedules is crucial to ensure the IRS processes your return correctly.
Schedule K-1: A Key Form for Shareholders
Since S Corporations don’t pay corporate taxes, each shareholder must report their share of the company’s income, deductions, and credits on their personal tax return. Schedule K-1 (Form 1120-S) provides this breakdown. Every shareholder must receive a copy, and the corporation must file it along with Form 1120-S.
Supplementary Forms
Depending on your business activities, you may also need to attach:
- Schedule D (Form 1120-S) – Reports capital gains, losses, and built-in gains.
- Form 4797 – Required for sales of business property.
- Form 8949 – Used for reporting sales and other dispositions of capital assets.
- Form 8825 – If the S Corporation earns rental real estate income.
- Form 1125-A – Needed for reporting Cost of Goods Sold (if applicable).
- Form 1125-E – If the corporation pays compensation to officers.
- Form 8050 – For direct deposit of a corporate tax refund.
- Form 3800 – Used to claim the General Business Credit.
- Form 8941 – If the corporation is claiming the Small Employer Health Insurance Credit.
- Form 6252 – If the business has installment sale income.
- Form 4136 – To claim a credit for federal tax paid on fuels.
- Form 8996 & 8997 – If investing in a Qualified Opportunity Fund (QOF).
- Form 8938 – If the corporation has specified foreign financial assets.
- Schedule K-2 & K-3 (Form 1120-S) – Required if the corporation has international tax items.
The IRS requires all schedules and forms to be attached in a specific order, with Schedule K-1, Schedule D, and other required forms placed after page 5 of Form 1120-S. Supporting statements and attachments should be included last, and each should clearly list the corporation’s name and EIN.
Fillable Form 1120-S
Easily complete your IRS Form 1120-S, including the Schedule K-1, using our fillable form tool. Simply enter the required information about your S Corporation, including income, deductions, and shareholder details. Once you’ve filled out the form, you can download it for submission to the IRS.
Where to File
The filing location for Form 1120-S depends on whether you’re mailing a paper return or filing electronically.
1. E-Filing (Required for Many S Corporations)
Most S corporations must e-file Form 1120-S if they file 10 or more tax returns in a calendar year, including employment tax, excise tax, and information returns. The IRS allows electronic filing for:
- Form 1120-S and related schedules
- Form 7004 (extension request)
- Employment tax returns (Forms 940, 941, 944)
- Form 1099 and other information returns
If your corporation qualifies for e-filing, you can file using IRS-approved e-file providers or tax software. If e-filing is not an option, you may request a waiver from the requirement.
2. Where to Mail
If your corporation is not required to e-file, you can mail your return to the correct IRS address based on location and total assets:
For corporations in these states:
Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia, Wisconsin
-
Less than $10 million in assets (no Schedule M-3):
Department of the Treasury, Internal Revenue Service, Kansas City, MO 64999-0013 -
$10 million or more in assets OR if filing Schedule M-3:
Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0013
For corporations in these states:
Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Hawaii, Idaho, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wyoming
-
Any amount of assets:
Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0013
For corporations outside the U.S.:
-
Foreign country or U.S. territory:
Internal Revenue Service, P.O. Box 409101, Ogden, UT 84409
Frequently Asked Questions
Can you deduct stock losses on an 1120-S Form?
Yes, but with limitations. An S Corporation itself doesn’t deduct stock losses in the same way a C Corporation does. Instead, stock losses (capital losses) pass through to shareholders and are reported on their personal tax returns via Schedule K-1 (Form 1120-S).
Can you amend Form 1120-S?
Yes, you can amend Form 1120-S if you need to correct errors in income, deductions, credits, or shareholder allocations. To do this, you must file Form 1120-S with the corrected information and check the “Amended Return” box at the top of the form. An amended return must generally be filed within three years of the original filing date (or within two years of paying tax, whichever is later).
Does 1120-S file Form 1099-INT for interest?
Yes, an S Corporation must file Form 1099-INT if it paid $10 or more in interest to another person or business during the tax year. This form reports interest income paid to recipients, such as investors, lenders, or vendors. If your S Corporation received interest income, it should be reported on Form 1120-S, Schedule K and Schedule K-1, where it passes through to shareholders.
