Key Tax Season Deadlines for Monotelo Small Business Clients in 2026

RJ Richter
2 days ago
2 min read

As the 2026 tax season gets underway, our goal is to ensure that all of our small business clients experience an easy and stress-free filing. The following dates highlight essential deadlines for S-Corps, partnerships, and C-Corporations—these are intended to keep you organized, help you avoid penalties, and clarify what you can expect from us.

Feel free to bookmark this page or revisit it during the season; it's your key resource for the most important tax milestones.

Key IRS Dates:

Jan 13: IRS begins accepting most business returns.
Jan 15: Final 2025 estimated tax payment due.
Jan 26: IRS starts processing federal 1040 returns.
Jan 31: Deadline for employers to send W-2s and certain 1099 forms (1099-NEC, 1099-MISC, 1099-K).
Mar 16: Filing deadline for S-Corp and partnership returns; extension requests must be filed by this date. Extensions do not extend tax payment deadlines.
Apr 15: C-Corp return and 1st quarter 2026 estimated tax payments due. Personal 1040 returns are also due, but S-Corp and Partnership filings must be complete first.

Monotelo Client-Specific Dates:

Jan 15: Soft Close—Upload your complete P&L and balance sheet by this date for guaranteed filing by Mar 8.
Jan 20: Submit all payroll and contractor info by this date for timely W-2/1099 issuance.
Jan 31: Hard Close—Documents uploaded by this date guarantee S-Corp or partnership return filing by Mar 15.
Feb 1: Corporate documents uploaded after this date will result in an automatic extension for your protection, though taxes are still due as scheduled.

How to Prepare:

Upload all relevant financials and supporting documents to your client portal early to ensure prompt and accurate filing.
Verify subcontractor, vendor, and employee details in advance to avoid form delays.
Contact Monotelo with questions or if you need assistance.

Staying informed of these deadlines helps minimize stress and ensures timely filings. We're here to support you throughout the process.

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