Key 2024 Deadlines for 401(k) Plan Sponsors

Birthdays, wedding anniversaries, and 401(k) plan compliance deadlines. Some dates are worth saving more than others. Keep reading for important deadlines associated with your 401(k) plan.

illustration of calendar with dollar sign sticker

Plan sponsors have several responsibilities throughout the year to keep their plan operating in compliance with federal regulations. We’ve listed some key 2024 deadlines and links to more information below to make your life a little easier. If a deadline falls on a weekend, it’s safe to submit the previous business day unless otherwise noted. Please also keep in mind there may be additional state regulations applicable to your plan not listed here.

January

Saturday, Jan. 13, 2024

  • Betterment at Work loads the prior year census template and compliance questionnaire to plan sponsors’ Compliance Hubs. Plan sponsors have until Tuesday, Jan. 31 to complete and submit both documents.

Wednesday, Jan. 31, 2024

  • Send Form W-2 to your employees.
  • Submit Form W-2 to the Social Security Administration. 
  • Submit the prior year census data and compliance questionnaire to Betterment at Work.
  • Submit Annual Return of Withheld Federal Income Tax (Form 945) to the IRS. If you’ve made all your deposits on time and in full, then the due date is Saturday, Feb. 10.
  • Send Form 1099-NEC to both the IRS and your employees.
  • Betterment at Work makes IRS Forms 1099-R available to participants.

February

Thursday, Feb. 1, 2024

  • Post the prior year’s OSHA Summary of Illness and Injuries in your workplace between February 1 and March 2.

Wednesday, Feb. 28, 2024

For Applicable Large Employers (ALE)

  • Submit paper Forms 1094-C and 1095-C to the IRS. If you intend to e-file your forms, then the deadline is Sunday, March 31. 

For self-insured, non-ALE companies

  • Submit paper Forms 1094-B and 1095-B to the IRS. If you intend to e-file your forms, then the deadline is Sunday, March 31. Note: Form 1095-B must be filed electronically if the reporting entity is required to file 250 or more returns.

March

Friday, March 1, 2024

For companies that participate in a Multiple Employer Welfare Arrangement (MEWA)

  • Submit your Form M-1 to the IRS.

Saturday, March 2, 2024

For Applicable Large Employers (ALE)

  • Send Forms 1095-C to employees.

For self-insured, non-ALE companies

  • Send Forms 1095-B to employees.

For companies with 250 or more employees in an industry covered by the recordkeeping regulation (or 20-249 employees in high risk industries)

  • E-file your OSHA Summary of Illness and Injuries for 2023.

Friday, March 15, 2024

  • Make refunds to participants for failed ADP/ACP tests(s), if applicable. As the plan sponsor, you must approve corrective action by your 401(k) provider by this date. Failure to meet this deadline could result in a 10% tax penalty for plan sponsors.

For S-Corps and LLCs taxed as Partnerships

  • Employer contributions (e.g., profit sharing, match, Safe Harbor) are due for deductibility.

For S-Corps and Partnerships

  • Deadline to establish a traditional (non-Safe Harbor) plan for the prior tax year, unless the tax deadline has been extended.

Sunday, March 31, 2024

  • File Form 1099s electronically with the IRS.

For companies with 100+ employees

  • Submit your EEO-1 report.

April

Monday, April 1, 2024

  • Confirm initial Required Minimum Distributions (RMDs) were taken by participants who turned 73 before previous year-end, are retired/terminated, and have a balance.

For companies in Maine with 5+ employees

  • Deadline to comply with Maine’s retirement plan mandate.

Tuesday, April 9, 2024

  • Report employees who participated in multiple plans that have excess deferrals (402(g) excess) to Betterment.

Monday, April 15, 2024

  • Tax Day
  • Deadline to complete corrective distributions for 402(g) excess deferrals.

For C-Corps, LLCs taxed as C-Corps, or sole proprietorships

  • Employer contributions (e.g., profit sharing, match, Safe Harbor) are due for deductibility.

For C-Corps and Sole Props

  • Deadline to establish a traditional (non-Safe Harbor) plan for the prior tax year, unless the tax deadline has been extended.

Tuesday, April 30, 2024

  • File Form 941 (Employer’s Quarterly Federal Tax Return) with the IRS.

May

Wednesday, May 15, 2024

For non-profit companies

  • Tax returns due

June

Sunday, June 30, 2024

  • Deadline for EACA plan refunds to participants for failed ADP/ACP tests(s). Failure to meet this deadline could result in a 10% tax penalty for plan sponsors.

July

Monday, July 1, 2024

  • Mid-Year Benefits Review: Remind employees to take advantage of any eligible voluntary benefits.

Wednesday, July 31, 2024

  • If your plan was amended, this is the deadline to distribute Summary of Material Modifications (SMM) to participants.
  • File Form 941 (Employer’s Quarterly Federal Tax Return) with the IRS.
  • Electronically submit Form 5500 (and third-party audit, if applicable) OR request an extension (Form 5558). Betterment at Work prepares these forms on our plan sponsors’ behalf, with plan sponsors being responsible for filing them electronically.

For self-insured companies

August

Thursday, Aug. 1, 2024

For NEW Betterment at Work 401(k) plans

  • Deadline to sign a services agreement with Betterment at Work in order to establish a new Safe Harbor 401(k) plan for 2025. Deferrals must be started by Tuesday, Oct. 1, 2024.

September

Sunday, Sept. 15, 2024

For S-Corps and Partnerships

  • Deadline to establish a traditional (non-Safe Harbor) plan for the prior tax year if the tax deadline has been extended.

Monday, Sept. 30, 2024

  • Distribute Summary Annual Report (SAR) to your participants and beneficiaries. If a Form 5500 extension is filed, then the deadline to distribute is Sunday, Dec. 15, 2024.

October

Tuesday, Oct. 1, 2024

  • Deadline to establish a new Safe Harbor 401(k) plan. The plan must have deferrals for at least 3 months to be Safe Harbor for this plan year.

Tuesday, Oct. 15, 2024

  • Electronically submit Form 5500 (and third-party audit if applicable) if granted a Form 5558 extension. Betterment at Work prepares these forms on our plan sponsors’ behalf, with plan sponsors being responsible for filing them electronically.

For C-Corps and Sole Props

  • Deadline to establish a traditional (non-Safe Harbor) plan for the prior tax year if the tax deadline has been extended.

For companies that offer prescription drug coverage to Medicare-eligible employees

  • Notify Medicare-eligible enrollees of creditable coverage for prescription drugs.

Thursday, Oct. 31, 2024

  • File Form 941 (Employer’s Quarterly Federal Tax Return) with the IRS.

November

Friday, Nov. 1, 2024 

  • Deadline to request an amendment to make a traditional plan a 3% Safe Harbor non-elective plan for the 2024 plan year. Amendment must be executed and sent by Sunday, December 1, 2024.
  • Deadline to request an amendment to make a traditional plan a Safe Harbor match plan for the 2024 plan year. Amendment must be executed and sent by Sunday, December 1, 2024.

December

Sunday, Dec. 1, 2024

  • Betterment at Work prepares 2025 Annual Notices (see subullets below) and sends relevant notices to our plan sponsors for distributing to participants. Plan sponsors to disseminate paper copies if required.
  • Deadline for plan sponsors to distribute notices (if applicable) to participants for 2025 plan year:
  • Deadline to execute amendment to make a traditional plan a 3% Safe Harbor nonelective plan for the 2024 plan year.
  • Deadline to execute amendment to make a traditional plan a Safe Harbor match plan for the 2024 plan year.

Sunday, Dec. 15, 2024

  • Distribute Summary Annual Report (SAR) to participants, if granted a Form 5558 extension.

Tuesday, Dec. 31, 2024

  • Deadline to post required workplace notices in conspicuous locations. 
  • Deadline to execute amendment to make a traditional plan a 4% Safe Harbor nonelective plan for the 2023 plan year.
  • Deadline to make Safe Harbor and other employer contributions for 2023 plan year.
  • Deadline for annual Required Minimum Distributions (RMDs).

For companies that failed ADP/ACP compliance testing

  • Deadline to distribute ADP/ACP refunds for the prior year; a 10% excise will apply.
  • Deadline to fund a QNEC for plans that failed ADP/ACP compliance testing.

Remaining 2023 Deadlines

Friday, Dec. 1, 2023

  • Betterment at Work prepares 2024 Annual Notices (listed below) and sends relevant notices to our plan sponsors for distributing to participants. Plan sponsors to disseminate paper copies if required.
  • Deadline for plan sponsors to distribute notices (if applicable) to participants for 2024 plan year:
  • Deadline to execute amendment to make a traditional plan a 3% Safe Harbor nonelective plan for the 2023 plan year.
  • Deadline to execute amendment to make a traditional plan a Safe Harbor match plan for the 2024 plan year.

Friday, Dec. 15, 2023

  • Distribute Summary Annual Report (SAR) to participants, if granted a Form 5558 extension.

Sunday, Dec. 31, 2023

  • Post required workplace notices in conspicuous locations.
  • Deadline to execute amendment to make a traditional plan a 4% Safe Harbor nonelective plan for the 2022 plan year.
  • Deadline to make Safe Harbor and other employer contributions for 2022 plan year.
  • Deadline for annual Required Minimum Distributions (RMDs).

For companies that failed ADP/ACP compliance testing

  • Deadline to distribute ADP/ACP refunds for the prior year; a 10% excise will apply.
  • Deadline to fund a QNEC for plans that failed ADP/ACP compliance testing.