- Business tax deadlines 2025: Corporations and LLCs
- General business tax deadlines for 2025
- November 1, 2024
- Jan 31, 2025
- Feb 17, 2025
- Corporation tax deadlines
- February 28, 2025: Form 3921, if filing by mail
- March 17, 2025: Form 1120-S (S-corps)
- March 31, 2025: Form 3921, if filing electronically
- April 15, 2025: Form 1120 (C-corps)
- LLC tax deadlines
- March 15, 2025: Form 1065
- March 17, 2025: Form K-1
- Sole proprietor tax deadlines
- April 15, 2025: Schedule C (Form 1040)
- Business tax deadlines 2024 for Corporations and LLCs
- Corporation tax deadlines
- February 28, 2024: Form 3921, if filing by mail
- March 15, 2024: Form 1120-S (S-corps)
- April 1, 2024: Form 3921, if filing electronically
- April 15, 2024: Form 1120 (C-Corporation)
- LLC tax deadlines
- March 15, 2024: Form 1065
- March 15, 2024: Form K-1
- Sole proprietor tax deadlines
- April 15, 2024: Schedule C (Form 1040)
The 2025 deadline to file individual income tax returns for 2024 is April 15, 2025. Tax deadlines vary for startups and other businesses classified as corporations and limited liability companies (LLC).¹
Here are the key business tax deadlines* and important dates for corporations (both C-corps and S-corps), LLCs, and sole proprietorships for the 2024 tax year:
*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. ¹Unless otherwise noted, in this article we classify LLCs as pass-through entities that have not elected to be taxed as corporations.
General business tax deadlines for 2025
November 1, 2024
All business entities that plan to file 10 or more returns in 2025 are required to have their own Transmitter Control Code (TCC) in order to file taxes electronically (e-file). The deadline to request a TCC number via the IRS’s Filing Information Returns Electronically (FIRE) application was November 1, 2024, for the 2025 tax filing year.
Jan 31, 2025
By January 31, 2025, businesses must provide copy B of Form 3921 to employees. The end of January is also the deadline to file and send W-2s to employees.
Feb 17, 2025
By February 17, 2025, businesses must send form 1099-B to employees.
Jump ahead if you're looking for Tax Deadlines from 2024Corporation tax deadlines
Tax deadlines for C-corporations and S-corporations in 2025 are as follows:
February 28, 2025: Form 3921, if filing by mail
Who must file?
Every corporation that had an employee exercise an ISO (incentive stock option) 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 deadline for filing Form 3921 electronically is March 31 (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 incentive stock option by an employee who is a nonresident alien and does not receive a W-2 form.
For employees:
-
Employees who exercised incentive stock options during 2024 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 17, 2025: Form 1120-S (S-corps)
Who must file?
S-corporations must file Form 1120-S. The deadline for C-corporations is generally April 15 (see more below).
Good to know:
-
This deadline applies to 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, 2025) 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, 2025: Form 3921, if filing electronically
Who must file?
Every corporation that had an employee exercise an ISO (incentive stock option) 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 February 28 (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 IRS Filing Information Returns Electronically (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 incentive stock option by an employee who is a nonresident alien and does not receive a W-2 form
For employees:
-
Employees who exercised incentive stock options during 2024 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, 2025: Form 1120 (C-corps)
Who must file?
C-corporations must file Form 1120 by April 15, 2025.
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.
LLC tax deadlines
Tax deadlines for LLCs in 2025 are as follows:
March 15, 2025: Form 1065
Who must file?
LLC and other domestic partnerships must file Form 1065 by March 15, 2025.
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, 2025) 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 17, 2025: Form K-1
Who must distribute?
LLCs and other entities that “pass through” taxes to their partners must distribute a Schedule K-1 Form by March 17, 2025.
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. The K-1 form details the partner’s share of the partnership’s income/losses, credits, and deductions for the year.
-
Form K-1s should be circulated to members of the LLC by March 17, 2025, unless an extension is filed, in which case they will not be ready for circulation until September 15, 2025.
-
There isn't a hard and fast deadline for K-1s. They should be issued when Form 1065 is filed and complete (March 15, 2025).
Sole proprietor tax deadlines
Tax deadlines for sole proprietors in 2025 are as follows:
April 15, 2025: Schedule C (Form 1040)
Who must file?
Sole proprietors 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
Business tax deadlines 2024 for Corporations and LLCs
Note: If you filed an extension for your 2023 taxes, the deadline to file your extended return was October 15, 2024. The 2024 deadline to file individual income tax returns for 2023 was April 15, 2024.
Below are the key business tax deadlines and important dates for corporations (both C-corps and S-corps), LLCs, and sole proprietorships from the 2023 tax year:
Note: 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.
Corporation tax deadlines
Tax deadlines for C-corporations and S-corporations in 2024 were as follows:
February 28, 2024: Form 3921, if filing by mail
Who must file?
Every corporation that had an employee exercise an ISO (incentive stock option) during the tax year must file copy A of Form 3921. A form must be filed for each employee who exercised an ISO.
Good to know:
-
This is the deadline for filing by mail; the deadline for filing Form 3921 electronically is April 1 (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 incentive stock option by an employee who is a nonresident alien and does not receive a W-2 form.
For employees:
-
Employees who exercised incentive stock options during 2023 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, 2024: Form 1120-S (S-corps)
Who must file?
S-corporations (deadline for C-corporations is generally April 15; see below).
Good to know:
-
This deadline applies to 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 could have received an extension (to September 16, 2024) 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.
April 1, 2024: Form 3921, if filing electronically
Who must file?
Every corporation that had an employee exercise an ISO (incentive stock option) during the tax year must file copy A of Form 3921. 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 February 28 (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 IRS Filing Information Returns Electronically (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 incentive stock option by an employee who is a nonresident alien and does not receive a W-2 form
For employees:
-
Employees who exercised incentive stock options during 2023 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, 2024: Form 1120 (C-Corporation)
Who must file?
C-corporations
Good to know:
-
This deadline applies to C-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.
-
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.
LLC tax deadlines
Tax deadlines for LLCs in 2024 were as follows:
March 15, 2024: Form 1065
Who must file?
Limited liability companies (LLC) and other domestic partnerships.
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 could have received an extension (to September 16, 2024) 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 15, 2024: Form K-1
Who must distribute?
Limited liability companies (LLCs) and other entities that “pass through” taxes to their partners.
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. The K-1 form details the partner’s share of the partnership’s income/losses, credits, and deductions for the year.
-
Form K-1s should have been circulated to partners of the LLC by March 15, 2024, unless an extension is filed, in which case they will not be ready for circulation until September 16, 2024.
-
There isn't a hard and fast deadline for K-1s. They should be issued when Form 1065 is filed and complete (March 15, 2024).
Sole proprietor tax deadlines
Tax deadlines for sole proprietors in 2024 were as follows:
April 15, 2024: Schedule C (Form 1040)
Who must file?
Sole proprietors 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