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The 2026 Plan Sponsor Calendar for 401(k) deadlines

For easy reference all year long, we recommend bookmarking it.

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Feb 1, 2026
Employer deadline
Post the prior year’s OSHA Summary of Illness and Injuries in the workplace between February 1 and April 30, 2026.
Start of Black History Month

Feb 2, 2026
Employer deadlines:
Submit Form W-2 to the Social Security Administration.
Annual Return of Withheld Federal Income Tax (Form 945) due for 2025.
Send Form 1099-NEC to both the IRS and employees.
Send Form W-2 to employees.
IRS Forms 1099-R available to participants.
Betterment deadline: Deadline for plan sponsors to submit prior year census data and compliance questionnaire to Betterment.

Feb 13, 2026
Employer deadline
Deadline to send quarterly participant statements for current 401(k) plan year (typically sent within a few days of quarter end).

Feb 14, 2026
Valentine’s Day

Feb 16, 2026
President’s Day

Feb 17, 2026
Chinese New Year

Feb 18, 2026
Ash Wednesday

Feb 28, 2026
Employer deadlines:
Applicable Large Employers (ALE): Submit Forms 1094-C and 1095-C to the IRS (paper filing). If e-filing, the deadline is March 31, 2026.
Self-insured companies not considered ALEs: Submit Forms 1094-B and 1095-B to the IRS (paper filing). E-file deadline is March 31, 2026. Form 1095-B must be filed electronically if 250+ returns.
Mar 1, 2026
Start of Women’s History Month

Mar 2, 2026
Companies in MEWA: Submit Form M-1 to the DOL.
Companies with 250+ employees (or 20–249 in high-risk industries): E-file OSHA Summary for 2025.
Applicable Large Employers (ALE): Send Form 1095-C to employees.
Self-insured, non-ALE: Send Form 1095-B to employees.

Mar 6, 2026
National Employee Appreciation Day

Mar 8, 2026
Daylight Savings Time begins
International Women’s Day

Mar 16, 2026
Employer deadlines:
Employer contributions (profit sharing, match, Safe Harbor) due for deductibility for S-Corps and LLCs taxed as Partnerships.
Deadline for S-Corps and Partnerships to establish a traditional (non-Safe Harbor) plan for the prior tax year unless tax deadline is extended.
401(k) provider & employers: Deadline for ADP/ACP test refunds. Plan Sponsor must approve corrective action to avoid 10% penalty.

Mar 17, 2026
St. Patrick’s Day

Mar 19–20, 2026
Eid al-Fitr

Mar 31, 2026
Companies with 100+ employees: Submit your EEO-1 report.
Deadline to file Form 1099s electronically.
Apr 1, 2026
April Fool’s Day
Educational opportunity: Financial Literacy Month begins
Passover begins
Employer deadline: Confirm Initial RMDs for participants who turned 73 before prior year-end.

Apr 2, 2026
World Autism Awareness Day

Apr 5, 2026
Easter

Apr 7, 2026
Educational opportunity: World Health Day

Apr 9, 2026
Passover ends
Betterment deadline: Report employees with excess deferrals (402(g)) to Betterment.

Apr 15, 2026
Tax Day
Employer deadline: Employer contributions due for deductibility (C-Corps, LLCs taxed as C-Corps, sole proprietorships).
401(k) provider: Complete corrective distributions for 402(g) excess deferrals.

Apr 22, 2026
Earth Day

Apr 30, 2026
Form 941 due (Employer’s Quarterly Federal Tax Return).
July 1, 2026
Mid-year benefits review: Encourage employees to use eligible voluntary benefits.

July 4, 2026
Independence Day

July 26, 2026
National Parents’ Day

July 29, 2026
Employer deadline: Distribute Summary of Material Modifications (SMM) to participants (if plan amended).

July 31, 2026
Self-insured companies: Submit the PCORI fee to the IRS.
401(k) provider & employers: File Form 5500 electronically or request Form 5558 extension. Betterment prepares forms; sponsor files electronically.
Employer deadline: Form 941 due.
Oct 1, 2026
Educational opportunity: Start of National Disability Employment Awareness Month
Employer deadline: Establish new Safe Harbor 401(k) plan (must have 3 months of deferrals).

Oct 10, 2026
Educational opportunity: World Mental Health Day

Oct 12, 2026
Indigenous Peoples’ Day

Oct 15, 2026
Employer deadlines:
Establish traditional (non-SH) plan for prior tax year if extended.
Notify Medicare-eligible employees of creditable prescription drug coverage.
File Form 5500 if Form 5558 extension granted (Betterment prepares; sponsor files).

Oct 18–24, 2026
National Retirement Security Week

Oct 20–21, 2026
Yom Kippur

Oct 31, 2026
Halloween
Nov 1, 2026
Daylight Savings Time ends

Nov 2, 2026
Employer deadline: Form 941 due.

Nov 3, 2026
Employer deadlines:
Amend plan to make a 3% Safe Harbor non-elective plan for 2025 plan year (execute and send by Dec 1).
Amend plan to make a Safe Harbor match plan for 2026 plan year (execute and send by Dec 1).

Nov 11, 2026
Veterans Day (observed)

Nov 13, 2026
401(k) provider: Send quarterly participant statements.

Nov 26, 2026
Thanksgiving

Nov 28, 2026
Small Business Saturday
Dec 1, 2026
401(k) provider & employers: 2025 Annual Notices sent by Betterment. Sponsors distribute as needed.
Employer deadlines: Distribute notices for 2027 plan year (Safe Harbor, QDIA, Automatic enrollment).
Execute and send amendments for:
• 3% Safe Harbor nonelective plan (2026 plan year)
• Safe Harbor match plan (2027 plan year)

Dec 4, 2026
First day of Hanukkah

Dec 15, 2026
Employer deadline: Distribute Summary Annual Report (SAR) if 5500 extension granted.

Dec 24, 2026
Christmas Eve

Dec 25, 2026
Christmas

Dec 26, 2026
Kwanzaa

Dec 31, 2026
New Year’s Eve
Employer deadlines:
Distribute ADP/ACP refunds for prior year (10% excise applies).
Fund QNEC for failed ADP/ACP testing.
Execute amendment for 4% Safe Harbor nonelective plan for 2025 plan year.
Make Safe Harbor and employer contributions for 2025 plan year.
Distribute Annual Required Minimum Distributions (RMDs).
Post workplace notices in visible locations.

The 2026 Plan Sponsor Calendar for 401(k) deadlines

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