Form 5500 for a 401(k) plan: the form, the schedules and the audit

Every covered 401(k) files

Under the 2025 Instructions for Form 5500, Section 1: Who Must File, pages 2 and 3, the pension plans that file include profit-sharing, stock bonus, money purchase and 401(k) plans, 403(b)(1) annuity and 403(b)(7) custodial account arrangements, IRAs an employer establishes under Code section 408(c), and SIMPLE 401(k) plans.

No contributions this year, a frozen plan, a plan being wound down: all still file. The one 401(k) that does not file Form 5500 is the solo plan covering only the owner, or the owner and spouse. That plan files Form 5500-EZ, and only for a year its combined year-end assets are over $250,000 or its final year.

Step one: count the right people

From plan years beginning in 2023, a defined contribution pension plan counts the participants with account balances at line 6g(1), except that a plan checking the first return box uses the end of year figure at line 6g(2); welfare and defined benefit plans still count total participants at line 5, under 88 FR 11984.

For a 401(k) the count is participants with account balances, not everyone eligible. A company with many eligible employees who never enrolled can have a small plan. A brand new plan counts line 6g(2), account balances as of the end of the plan year. The 80-120 rule, which can keep a plan between 100 and 120 on the small side, is set out on the small or large plan page.

Step two: which form

A small 401(k) usually files the short form.

Under the 2025 Instructions for Form 5500, Quick Reference Chart, note 2, page 14, a plan can use Form 5500-SF if the plan had fewer than 100 participants at the beginning of the plan year, is exempt from the annual accountant's audit other than by enhanced bonding, holds all of its assets in secure investments with a readily determinable fair market value, holds no employer securities, and is not a multiemployer plan, a plan required to file Form M-1, a pooled employer plan or a plan in a DCG.

Most small 401(k) plans invested in mutual funds through a recordkeeper meet those conditions. A plan holding employer stock, or an investment without a readily determinable value, does not, and files Form 5500 with Schedule I. A large 401(k) files Form 5500 with Schedule H.

Step three: the audit

Under 29 CFR 2520.103-1(b)(5), the annual report of a plan with 100 or more participants normally includes a report from an independent qualified public accountant.

For a 401(k) that means the audit starts when the plan files as large, which turns on account balances at the start of the year. Growth in headcount alone does not trigger it. Enrollment does. A plan that adopts automatic enrollment can cross the line in one year, so check the count before the year starts rather than when the return is due.

Step four: which schedules

A large 401(k) commonly attaches Schedule H, Schedule C if any provider was paid $5,000 or more directly or indirectly, Schedule D if it holds collective trusts or pooled separate accounts, and Schedule A for any insurance contract such as a group annuity. Schedule G follows from certain yes answers on Schedule H. Schedule R is aimed at defined benefit plans and others subject to Code section 412, and the instructions list further cases, so check them for the plan in hand. The schedules page sets out each one.

Dates, and the form that travels separately

A 401(k) with a calendar plan year is due on 31 July, or 15 October with a timely Form 5558. Other plan years differ, and the due dates page lists them all. A plan with separated participants who left vested balances may also owe Form 8955-SSA, which goes to the IRS, not EFAST2; the Form 8955-SSA page covers it. If any year is already late, the clock prices it on both counts.