- Business tax deadlines 2027: Corporations and LLCs
- General business tax deadlines for 2027
- November 3, 2026
- February 1, 2027
- February 16, 2027
- Corporation tax deadlines for 2027
- March 1, 2027: Form 3921, if filing by mail
- March 15, 2027: Form 1120-S (S corps)
- March 31, 2027: Form 3921, if filing electronically
- April 15, 2027: Form 1120 (C corps)
- Company tax reporting requirements
- LLC tax deadlines for 2027
- March 15, 2027: Form 1065
- March 15, 2027: Form K-1
- March 15, 2027: Form 1042 and Forms 1042-S
- Sole proprietor tax deadlines for 2027
- April 15, 2027: Schedule C (Form 1040)
- Payroll and contractor filing deadlines for 2027
- Business tax deadline extensions
- Manage equity taxes with Carta Equity Advisory
- Frequently asked questions about business tax deadlines
The deadline to file individual income tax returns for the 2026 tax year is April 15, 2027. Federal tax deadlines vary for startups and other businesses depending on business structure—whether classified as corporations, limited liability companies (LLC), or other entity types.*
Here are the key business tax deadlines** and important dates for corporations (both C corps and S corps), LLCs, and sole proprietorships for the 2026 tax year:
*Unless otherwise noted, this article classifies LLCs as pass-through entities that have not elected to be taxed as corporations.
**Deadlines vary based on the fiscal year an entity uses; make sure to check the IRS website for further details on when to file. Businesses can file for extensions.
Note that this article is for informational purposes only, and does not constitute legal, financial, accounting, or tax advice. You should consult a qualified professional advisor before making any decision or taking any action that may affect your business or interests. You further agree and acknowledge that this document has not been prepared with your specific circumstances in mind and may not be suitable for use in your business. Carta does not assume any liability for reliance on the information provided herein.
General business tax deadlines for 2027
November 3, 2026
All business entities that plan to file 10 or more returns in 2027 are required to have their own Transmitter Control Code (TCC) to file taxes electronically (e-file). The deadline to request a TCC number via the IRS's Filing Information Returns Electronically (FIRE) application is November 1, 2025, for the 2027 tax filing year.
New filers now apply through the IRIS Application for TCC. The IRS is retiring its Filing Information Returns Electronically (FIRE) system for the 2027 filing season (tax year 2026) and is no longer accepting new FIRE TCC applications. Going forward, the Information Returns Intake System (IRIS) will be the only e-file system for information returns.
February 1, 2027
By February 1, 2027, businesses must provide copy B of Form 3921 to employees.
Forms 1099-NEC (Non-employee Compensation) and most other 1099 Forms (1099-MISC, 1099-INT, 1099-DIV, 1099-K) are due.
This is also the deadline to file and send W-2 forms to employees.
February 16, 2027
By February 16, 2027, businesses must send form 1099-B to employees.
Corporation tax deadlines for 2027
Tax deadlines for C corporations and S corporations in 2027 are as follows:
March 1, 2027: Form 3921, if filing by mail
Who must file?
Every corporation that had an employee exercise an incentive stock option (ISO) during the tax year must file copy A of Form 3921 (employee ISO exercises). A form must be filed for each employee who exercised an ISO.
Good to know
This is the deadline for filing by mail; the filing deadline for Form 3921 electronically is March 31, 2027 (see below).
Filing late results in penalties, starting at $60 per form (meaning, per employee ISO exercise) if 30 days late and increasing from there.
A Form 3921 is not required for the exercise of an ISO by an employee who is a nonresident alien and does not receive a Form W-2.
For employees
Employees who exercised ISOs during 2026 are required to include that on their tax returns, since exercised ISOs are considered taxable income by the IRS.
The information needed to report this is included on Form 3921, which is provided to employees by their employer.
March 15, 2027: Form 1120-S (S corps)
Who must file?
S corporations must file Form 1120-S. The deadline for C corporations is generally April 15, 2027 (see more below).
Good to know
This deadline applies to calendar year filers—S corporations that use December 31 as the end of their fiscal tax year; check IRS guidelines for deadlines if your fiscal tax year ends on a different date.
S corps can receive an extension (to September 15, 2027) by filing Form 7004 (Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns) by the regular due date of the return.
March 31, 2027: Form 3921, if filing electronically
Who must file?
Every corporation that had an employee exercise an ISO during the tax year must file copy A of Form 3921 (employee ISO exercises). A form must be filed for each employee who exercised an ISO.
Good to know
This is the deadline for filing electronically; the deadline for filing Form 3921 by mail is March 1, 2027 (see above).
To file Form 3921 electronically, first you have to request authorization from the IRS to file electronically and receive a TCC. With that code, you can set up an account on the FIRE system. It can take several weeks to receive a TCC.
Filing late results in penalties, starting at $60 per form (meaning, per employee ISO exercise) if 30 days late and increasing from there.
A Form 3921 is not required for the exercise of an ISO by an employee who is a nonresident alien and does not receive a Form W-2.
For employees
Employees who exercised ISOs during 2026 are required to include that on their tax returns, since exercised ISOs are considered taxable income by the IRS.
The information needed to report this is included on Form 3921, which is provided to employees by their employer.
April 15, 2027: Form 1120 (C corps)
Who must file?
Tax Day, April 15, 2027, is the deadline for C corporations to file their business tax return using Form 1120, which covers its federal income tax obligations for the year.
Good to know:
This deadline applies to C corps that use December 31 as the end of their fiscal tax year; check IRS guidelines for deadlines if your fiscal tax year ends on a different date.
C corps can receive an extension by filing Form 7004 (Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns) by the regular due date of the return.
Company tax reporting requirements
Download our step-by-step guide to understand when and how to report equity-related taxes.
LLC tax deadlines for 2027
Tax deadlines for multi-member LLCs in 2027 are as follows:
Note: Single-member LLCs are typically treated like Schedule C sole proprietorships. (See below). Single-member LLCs that do not elect to be taxed as a corporation are considered “disregarded entities” by the IRS.
March 15, 2027: Form 1065
Who must file?
LLC and other domestic partnerships must file Form 1065 by March 15, 2027.
Good to know
As pass-through entities, partnerships typically don't pay tax on their income but rather pass through any profits or losses to its partners, who must declare such items on their returns.
LLCs can receive an extension (to September 15, 2027) by filing Form 7004 (Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns) by the regular due date of the return.
As a general practice, all partnership and LLC entities should file an extension every year, because making changes to a return after its deadline has become cumbersome with the Administrative Adjustment Request (AAR) process. Filing the extension allows the taxpayer an additional six months to supersede its filed return.
March 15, 2027: Form K-1
Good to know
As pass-through entities, partnerships and LLCs typically don't pay federal tax on their income but rather pass through any profits or losses to its partners, who must declare such items on their returns. The K-1 form details the partner's share of the partnership's income/losses, credits, and deductions for the year. Note partnerships with foreign partners may be required to withhold and pay tax for income allocated to those foreign partners. Also, states may apply taxes to pass-through entities.
Form K-1s should be circulated to members of the LLC by March 15, 2027, unless an extension is filed, in which case they will not be ready for circulation until September 15, 2027.
There isn't a fixed deadline for K-1s. They should be issued when Form 1065 is filed and complete (March 15, 2027). Often, a partnership will designate a deadline for delivering Schedule K-1s to its partners, so check the operating agreements and subscription documents.
March 15, 2027: Form 1042 and Forms 1042-S
Form 1042 reports withholding tax due for Fixed, Determinable, Annual or Periodic (FDAP) income that was paid to foreign persons. If a partnership has a foreign person as partner and is allocating FDAP income to them, they are required to report and possibly withhold and pay taxes on their behalf.
Form 1042 is due on March 15, 2027 for any FDAP payments made during the 2026 calendar year.
The deadline for filing Form 1042 may be automatically extended by filing form 7004 by March 15, 2027. Note that this is an extension for filing, but any tax or withholding due for these payments is due March 15, 2027 and cannot be extended.
Sole proprietor tax deadlines for 2027
Tax deadlines for sole proprietors in 2027 are as follows:
April 15, 2027: Schedule C (Form 1040)
Who must file?
Self-employed individuals, sole proprietors, and freelancers must use Schedule C (Form 1040) to report income or loss from a business they operated or a profession they practiced.
An activity qualifies as a business if:
Your primary purpose for engaging in the activity is for income or profit
You are involved in the activity with continuity and regularity
In addition to income taxes, sole proprietors owe self-employment tax on net earnings, which covers Social Security and Medicare contributions. To stay current, the IRS generally requires quarterly estimated tax payments throughout the year—due in April, June, September, and January. Missing these can result in underpayment penalties when the annual return is filed.
Payroll and contractor filing deadlines for 2027
If you have employees or pay independent contractors, a few more deadlines apply. You must furnish Form W-2 to employees and Form 1099-NEC to independent contractors by January 31, 2027.
Businesses with employees also carry recurring payroll tax obligations. You generally report income tax withholding and Social Security and Medicare taxes each quarter on Form 941, and you report federal unemployment tax once a year on Form 940. Tax deposits are typically made through the Electronic Federal Tax Payment System (EFTPS). A payroll provider often handles these filings, but the responsibility stays with you.
Business tax deadline extensions
Need more time? In most cases, a business can request an automatic six-month extension to file using Form 7004 by the original due date. Sole proprietors and single-member LLCs instead file Form 4868 with their personal return.
A tax extension moves the filing deadline to September 15, 2027 for S corporations and partnerships, and to October 15, 2027 for C corporations and sole proprietors.
An extension gives you more time to file, not more time to pay. Estimate your tax liability and pay it by the original deadline to avoid interest and underpayment penalties.
Manage equity taxes with Carta Equity Advisory
Equity events like ISO exercises and Form 3921 filings raise tax questions your team will bring to you. Carta Equity Advisory gives founders and employees direct access to tax and equity experts, so you can hand off complex questions instead of guessing your way through them. Its 1:1 sessions average 4.9 out of 5.0 in customer satisfaction across more than 4,700 sessions.
Request a demo to learn more.
Frequently asked questions about business tax deadlines
When are business taxes due in 2027?
It depends on your entity type. Calendar-year partnerships and S corporations file by March 15, 2027, while C corporations and sole proprietors file by April 15, 2027.
Is there an extension for LLC or S corp tax filing in 2027?
Yes. S corporations and partnerships, including multi-member LLCs, can file Form 7004 for an automatic six-month extension to September 15, 2027. Single-member LLCs use Form 4868 with the owner's personal return, which extends the deadline to October 15, 2027.
Does a tax extension give me more time to pay?
No, an extension moves your filing deadline, not your payment deadline, so estimate and pay any tax owed by the original due date to avoid interest and penalties.
When are quarterly estimated taxes due for a business?
For the 2027 calendar year, estimated tax payments are due April 15, June 15, and September 15, 2027, with the fourth installment due January 17, 2028. Owners of pass-through entities generally pay these on their personal returns.
What happens if I miss a business tax deadline?
Interest and penalties generally accrue from the missed date, so file as soon as you can; late Form 3921 filings, for example, start at $60 per form.
DISCLOSURE: This communication is on behalf of eShares, Inc. dba Carta, Inc. ("Carta"). This communication is for informational purposes only, and contains general information only. Carta is not, by means of this communication, rendering accounting, business, financial, investment, legal, tax, or other professional advice or services. This publication is not a substitute for such professional advice or services nor should it be used as a basis for any decision or action that may affect your business or interests. Before making any decision or taking any action that may affect your business or interests, you should consult a qualified professional advisor. This communication is not intended as a recommendation, offer or solicitation for the purchase or sale of any security. Carta does not assume any liability for reliance on the information provided herein. ©2026 Carta. All rights reserved. Reproduction prohibited.
