What Annual Notices Must a 401(k) Plan Send to Participants?
A 401(k) plan generates a surprising amount of paper, or these days, a surprising number of emails, and most of it exists because the law requires it rather than because anyone particularly wants to read it.
The short answer
A 401(k) plan is generally required to send participants several recurring annual disclosures, including a fee and investment disclosure, a notice about the plan’s default investment option if one applies, and, for plans using that design, a safe harbor notice. Each notice serves a distinct legal purpose, and together they’re meant to keep participants informed about costs, investment choices, and how the plan operates, even though in practice they often arrive as dense documents that are easy to set aside.
Fee and investment disclosures
One of the most consistent annual requirements is a disclosure of the plan’s fees and the investment options available within it. This typically breaks down administrative costs charged to the plan, any fees tied to specific investment choices, and performance information for each available fund, presented in a standardized format meant to make comparison easier. Because fees compound over decades the same way returns do, this is often the single most financially relevant document a participant receives each year, even though it rarely gets read with that level of attention.
Default investment notices
For participants who don’t actively choose their own investments — often because they were automatically enrolled — the plan typically has to disclose which default investment option their contributions are directed into and explain that they have the right to choose something different. This notice matters most for anyone unsure whether they’ve ever actively selected an investment lineup within their plan, since it identifies exactly where contributions are landing by default and how to change that if desired.
Safe harbor and matching notices
Plans that use a safe harbor design, which lets them skip certain nondiscrimination testing in exchange for meeting a defined contribution formula, are required to send an annual notice describing that formula, vesting terms, and eligibility rules, generally before the plan year begins. This is a distinct requirement from the fee disclosure and covers different information entirely, focused on what the employer is contributing rather than what the plan costs to run.
Notices about changes to the plan
When a plan changes something significant mid-year — a new investment option, a different match formula, a change in vesting schedule — participants are generally entitled to a notice describing that specific change, sometimes called a summary of material modifications. This is separate from the routine annual disclosures and exists specifically to flag changes as they happen rather than waiting for the next full plan document update. A plan’s overall structure and rules are also laid out in its summary plan description, which the plan’s fiduciaries are responsible for keeping accurate and accessible.
The bottom line
Skimming or ignoring these notices is common, but they’re often the fastest way to catch a change that affects take-home contributions or investment costs before it becomes a surprise on a later statement. A shift in the default fund, a change to the match formula, or a new administrative fee will typically show up in one of these disclosures well before it’s reflected in account performance. The recurring cycle of notices can feel like background noise, but each one is tied to a specific requirement meant to keep participants informed about cost, investment structure, or plan changes, and treating even a quick skim of each one as an annual checkpoint is a small habit that keeps a retirement account from drifting out of sync with what the participant actually intended.