2025 US Tax Due Dates & Deadlines: Guide for CPAs

US Tax season for 2025 is here and there are deadlines which CPAs must take care of. Missing these deadlines can cost high penalties and interest. To avoid missing such deadlines you should have a handy list of all the deadlines to start preparing for them priorly.

The 2025 tax filing season officially started on January 27, 2025, as announced by the IRS, giving tax professionals and their clients a clear timeline for preparation.

Key 2025 tax calendar overview

Let us have a look at the deadlines of the US calendar 2025 below.

January 2025 deadlines

January 15, 2025 – Final Estimated Tax Payment
The fourth quarter estimated tax payment for 2024 is due. Individual taxpayers and businesses must complete this payment to avoid penalties.

January 31, 2025 – Employment Tax Forms
Employers must mail out W-2s by January 31, 2025. This includes:

• Form W-2 (Wage and Tax Statement)
• Form 1099-MISC and 1099-NEC
• Form 1099-K for payment processors

Important business tax due dates 2025

Apart from the January deadlines, there are couple of other deadlines which needs to be kept in mind.

March 17, 2025 – Partnership and S Corporation Deadline

When are partnership tax returns due? Form 1065 for calendar year partnerships is due March 17, 2025 (March 15 falls on a Saturday).

This business tax return deadline applies to:

• Partnerships (Form 1065)
• S Corporations (Form 1120S)
• Multi-member LLCs taxed as partnerships

Important Note: March 17 is both the S Corp tax filing deadline AND the S Corp tax return extension request deadline.

April 15, 2025 – Individual and C Corporation Deadline

What day to file taxes for most taxpayers? April 15, 2025 is the deadline for taxpayers to file 2024 federal income tax returns (Form 1040 and 1040-SR).

This tax due date 2025 covers:

• Individual tax returns (Form 1040)
• C Corporations (Form 1120)
• Sole proprietorships (Schedule C)
• Single-member LLCs

C corp tax due date specifics:
C corporations need to file Form 1120 by April 15, 2025, if they are a calendar year business.

LLC tax due date breakdown

LLC tax due date varies by election:

Single-Member LLC:

• Disregarded entity: April 15, 2025 (with owner’s 1040)
• S Corp election: March 17, 2025

Multi-Member LLC:

• Partnership taxation: March 17, 2025
• S Corp election: March 17, 2025
• C Corp election: April 15, 2025

Business tax extension deadline

Corporate tax extension deadline provides crucial relief for unprepared returns:

• Partnerships/S Corps: Must file extension by March 17, 2025
• C Corporations: Must file extension by April 15, 2025

Tax extension deadline 2025 schedule

Critical Warning: Extensions grant time to file, not time to pay. Taxes owed must still be paid by the original due date to avoid penalties.

IRS tax due dates – Complete 2025 timeline

Quarterly Estimated Payment Schedule

Extended return deadlines

Deadline to file tax return with extensions:

• September 15, 2025 – Deadline for extended partnership and S corporation returns
• October 15, 2025 – Deadline for extended C corporation returns

Tax filing deadlines for businesses – Strategic planning

Corporate tax filing extension deadline strategy

Tax filing deadline for corporations requires careful planning:

1. Assess readiness by February 15th
2. File extensions before original due dates
3. Estimate tax liability accurately
4. Make required payments by original deadlines

Multi state business considerations

State tax deadlines for multi-state businesses often differ from federal dates:

• Some states require separate extensions
• Payment requirements may vary
• Conformity rules affect timing

Penalty avoidance for CPAs

Common tax penalties in 2025

Failure to File Penalty:

• 5% per month (maximum 25%)
• Applies when returns are late

Failure to Pay Penalty:

• 0.5% per month (maximum 25%)
• Charged on unpaid taxes

Estimated Tax Penalty:

• Applied when insufficient payments made
• Safe harbor: 100% of prior year tax (110% if AGI > $150,000)

IRS tax deadlines for CPAs 2025 – Best practices

Maximizing deductions before tax deadlines 2025:

• Review depreciation elections
• Consider Section 179 deductions
• Analyze retirement plan contributions
• Implement tax strategies before year-end

Filing strategies for tax professionals

Advising clients on 2025 tax deadlines

Tax deadline management for accountants involves:

1. Early client communication about required documents
2. Systematic deadline tracking using tax calendar software
3. Extension strategy discussions for complex returns
4. Penalty mitigation planning for late filers

CPAs managing tax deadlines for clients

Tax compliance for accountants in 2025 requires:

• Automated reminder systems
• Document request templates
• Extension filing procedures
• Payment deadline tracking

2025 Tax filing due dates for businesses – Action items

January Priorities

• Collect year-end documents
• Issue employment tax forms
• Make final estimated payments

February Priorities

• Begin return preparation
• Assess extension needs
• Review prior year audits

March Priorities

• File partnership/S corp returns
• Submit business extensions if needed
• Prepare individual returns

IRS Filing dates for Partnerships and Corporations

Partnership filing requirements

Business tax filing deadline for partnerships:

• Form 1065 due March 17, 2025
• K-1s must be issued to partners
• Extension available until September 15, 2025

Corporation filing requirements

Corporate tax return due date schedule:

• C Corps: April 15, 2025 (Form 1120)
• S Corps: March 17, 2025 (Form 1120S)
• Extensions add six months

FAQs