Open enrollment: is the yearly window when employees can sign up for, change, or drop their employer-sponsored benefits, such as health, dental, vision, FSA, and life insurance. Outside this period, most elections can only change after a qualifying life event.
Key takeaways
- Most employers hold open enrollment in October or November for a January 1 plan year.
- Windows usually run two to four weeks.
- Section 125 elections made at open enrollment are locked for the plan year, with limited exceptions.
- The ACA marketplace has its own open enrollment, which is separate from employer plans.
How open enrollment works
Open enrollment is the end of a process that starts months earlier. HR and the broker renew plans with carriers in the summer, finalize rates and contributions, update plan documents and the Summary of Benefits and Coverage, and load everything into the benefits system. Then employees review options and submit elections during the window.
After the window closes, HR audits elections, sends files to carriers, and updates payroll deductions for the first paycheck of the new plan year. Passive enrollment, where current elections roll over automatically, is common for medical plans, while FSAs usually require a new election every year.
Employees who miss the window generally wait until next year unless they have a qualifying life event, such as marriage or the birth of a child.
Open enrollment example
A 120-person company with a January 1 renewal might run this timeline:
| August to September | Renewal quotes, plan changes, contribution strategy |
|---|---|
| Early October | Load plans and rates into the benefits system, test enrollment |
| Late October | Announcement email, benefits guide, virtual Q&A |
| November 1 to 15 | Enrollment window open, reminders at midpoint and final two days |
| Late November | Audit elections, send carrier files, confirm payroll deductions |
Our open enrollment announcement and reminder templates cover the two messages that drive participation.
Why open enrollment matters for employers
Open enrollment is when employees feel the cost of health care most directly. KFF reported average family premiums of $26,993 in 2025, up 6% from the prior year, with workers paying $6,850 on average (KFF 2025 Employer Health Benefits Survey). Clear communication about what changed, and why, decides whether employees see the benefits package as valuable or as a pay cut.
It's also a peak workload for HR. Paper forms and spreadsheets produce errors that show up later as denied claims or wrong deductions. Benefits administration software with decision support, carrier connections, and automatic payroll updates is one of the clearest returns on HR technology.
Common open enrollment mistakes to avoid
Announcing changes too late
Give employees at least a week before the window opens to review changes.
Not requiring active FSA elections
Most FSAs need a new election each year. Rolling them over by default can cause problems.
Forgetting payroll
New deductions must be live for the first paycheck of the plan year.
Skipping the post-enrollment audit
Compare elections, carrier files, and payroll before the plan year starts.
Open enrollment: questions people also ask
When is open enrollment for employer benefits?
How long is open enrollment?
What happens if I miss open enrollment?
Is employer open enrollment the same as marketplace open enrollment?
Can I change my benefits after open enrollment?
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HRTally glossary entries are written by people who have run US payroll, benefits, and HR operations, then checked line by line against primary sources such as the IRS, Department of Labor, EEOC, and Bureau of Labor Statistics. Dollar limits and rates are for 2026 unless stated. We review every entry at least twice a year and whenever a rule changes. This page explains general rules and isn't legal or tax advice; state law can differ. Read our editorial standards.
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<blockquote>Open enrollment is the yearly window when employees can sign up for, change, or drop their employer-sponsored benefits, such as health, dental, vision, FSA, and life insurance. Outside this period, most elections can only change after a qualifying life event.</blockquote><p>Source: <a href="https://www.hrtally.com/hr-glossary/open-enrollment/">HRTally HR Glossary, Open enrollment</a></p>
Written by the HRTally Research Team
Our guides are written and reviewed by people with hands-on US HR, payroll, and HR technology experience. Legal and tax facts are checked against primary sources, such as the Department of Labor, IRS, EEOC, and USCIS, and linked at the end of each guide. Vendors never review or pay for our editorial content.