To qualify under IRS Code Section 401(a), a retirement plan must satisfy a connected set of requirements covering its written structure, who participates, how benefits vest, how contributions are distributed among employees, annual dollar limits, when money can and must come out, and ongoing IRS reporting. Meeting these requirements is what gives a 401(k), profit-sharing plan, or defined benefit pension its tax-deferred growth and lets the employer deduct contributions in the year they’re made.1Office of the Law Revision Counsel. 26 U.S. Code 401 – Qualified Pension, Profit-Sharing, and Stock Bonus Plans Falling short can cost the plan its qualified status, so the rules below are not optional design choices.
Written Plan and Trust
A qualified plan begins with a formal written document and a trust agreement. The plan document explains how the plan operates, who participates, how contributions are calculated, and when benefits are paid. The trust holds all plan assets separately from the employer’s own money, managed by a trustee for the sole benefit of participants and their beneficiaries.1Office of the Law Revision Counsel. 26 U.S. Code 401 – Qualified Pension, Profit-Sharing, and Stock Bonus Plans
The exclusive benefit rule is the backbone of the whole framework. Plan assets cannot be redirected to pay company expenses or fund corporate investments. The money belongs to the participants. Alongside this, the plan must be intended as a permanent arrangement, not a short-term tax play the employer shuts down after a few profitable years. If a plan does terminate, all accrued benefits must become fully vested for every affected participant immediately.
Who the Plan Must Cover
Section 410 sets floors, not ceilings, on eligibility. Employers can be more generous, but they cannot lock employees out longer than the statute allows.
Age and Service
A plan cannot require an employee to be older than 21 or to have worked more than one year of service before becoming eligible. A year of service means a 12-month period in which the employee works at least 1,000 hours.2Office of the Law Revision Counsel. 26 U.S. Code 410 – Minimum Participation Standards A plan may impose a two-year service requirement instead, but only if it provides 100% immediate vesting on all employer contributions when the employee enters. Once eligibility is met, entry must happen no later than the start of the next plan year.
Long-Term Part-Time Employees
Under SECURE 2.0, 401(k) plans must allow participation by long-term part-time employees who work at least 500 hours per year for two consecutive years. That threshold was lowered from three years under the original SECURE Act.3Internal Revenue Service. Additional Guidance With Respect to Long-Term, Part-Time Employees These employees must be permitted to make elective deferrals, though the employer is not required to match or make profit-sharing contributions for them. The rule also reaches ERISA-covered 403(b) plans.
Coverage Testing
Beyond individual eligibility, the plan overall must cover a broad enough share of the workforce. The simplest annual test is the ratio percentage test: the percentage of non-highly compensated employees (NHCEs) covered by the plan must equal at least 70% of the percentage of highly compensated employees (HCEs) covered. A plan that can’t pass that ratio may instead try the average benefit percentage test, under which the NHCE average benefit percentage must reach at least 70% of the HCE figure.4eCFR. 26 CFR 1.410(b)-5 – Average Benefit Percentage Test A third route, the nondiscriminatory classification test, asks whether the covered group represents a reasonable and nondiscriminatory classification.
Who Counts as a Highly Compensated Employee
Almost every nondiscrimination rule turns on the HCE/NHCE line. An employee is an HCE if they owned more than 5% of the business at any point in the current or preceding plan year, or if they earned more than $160,000 from the employer during the preceding year (the 2026 threshold).5Internal Revenue Service. COLA Increases for Dollar Limitations on Benefits and Contributions The employer may optionally narrow the compensation-based group to the top 20% of earners.6Internal Revenue Service. Identifying Highly Compensated Employees in an Initial or Short Plan Year Everyone else is an NHCE.
Vesting Minimums
Vesting determines when an employee permanently owns the employer-contributed portion of their account. Money the employee contributes from their own pay is always 100% vested immediately. Employer contributions must vest at least as fast as one of the statutory schedules, and the required speed depends on the plan type.7Office of the Law Revision Counsel. 26 USC 411 – Minimum Vesting Standards
Defined contribution plans like 401(k)s must use one of two schedules. A three-year cliff schedule vests employees at 0% until they complete three years of service, then jumps to 100%. A two-to-six-year graded schedule vests 20% after two years and adds another 20% each year until reaching 100% after six years.
Defined benefit pension plans follow slightly longer schedules. A five-year cliff schedule provides no vesting until five years of service, then full vesting. A three-to-seven-year graded schedule vests 20% after three years and rises by 20% per year to 100% after seven years.
These are minimums. An employer can vest faster, and any plan that terminates must fully vest every participant regardless of where they sit on the schedule.
Nondiscrimination in Contributions and Benefits
Section 401(a)(4) requires that the actual contributions or benefits provided by the plan not favor HCEs over NHCEs. Coverage testing measures who’s in the plan; this rule measures what those participants are getting.
The most direct way to satisfy the requirement is a safe harbor design. A safe harbor 401(k) automatically passes nondiscrimination testing because the employer commits to a minimum contribution for all eligible employees, either a match or a flat nonelective contribution. Plans without a safe harbor design must run the general test each year, comparing effective contribution or benefit rates between the two groups. The math is technical enough that most sponsors outsource it to a third-party administrator.
2026 Dollar Limits
Qualified plans operate within several overlapping annual caps. Blowing past any of them can put qualified status at risk.
Employee Elective Deferrals
For 2026, the maximum an employee can contribute to a 401(k) or similar plan through payroll deferrals is $24,500. Employees age 50 and older can add a catch-up contribution of up to $8,000, for a combined limit of $32,500. SECURE 2.0 also created an enhanced catch-up for employees aged 60 through 63, who may contribute an extra $11,250 rather than the standard $8,000, bringing their maximum to $35,750.8Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
Total Annual Additions
Section 415(c) caps the total amount flowing into a defined contribution account in a year from all sources combined, including employee deferrals, employer contributions, and reallocated forfeitures. For 2026, the ceiling is $72,000 or 100% of the participant’s compensation, whichever is less.9Internal Revenue Service. 2026 Amounts Relating to Retirement Plans and IRAs, as Adjusted for Changes in Cost-of-Living Catch-up contributions sit on top of the $72,000 and do not count against it.10Office of the Law Revision Counsel. 26 USC 415 – Limitations on Benefits and Contribution Under Qualified Plans
Compensation Cap
Section 401(a)(17) limits how much of an employee’s pay the plan can use in its benefit or contribution formula. For 2026, only the first $360,000 of compensation counts.9Internal Revenue Service. 2026 Amounts Relating to Retirement Plans and IRAs, as Adjusted for Changes in Cost-of-Living An executive earning $500,000 has their employer contribution calculated as though they earn $360,000. The rule keeps the tax subsidy from concentrating on the highest earners.
Distributions
Section 401(a) tax deferral is meant to run until retirement, not indefinitely. Several distribution rules govern when money must come out and how it is protected in the meantime.
Required Minimum Distributions
Section 401(a)(9) forces participants to start drawing down at a specified age. For 2026, the RMD starting age is 73, and the first distribution must be taken by April 1 of the year after the participant turns 73. For 401(k) and similar employer plans, participants who don’t own 5% or more of the business can delay RMDs until April 1 after the year they actually retire, if the plan allows.11Internal Revenue Service. Retirement Topics – Required Minimum Distributions (RMDs) Missing an RMD triggers a 25% excise tax on the shortfall, reduced to 10% if corrected within the statutory window.12Office of the Law Revision Counsel. 26 USC 4974 – Excise Tax on Certain Accumulations in Qualified Retirement Plans The starting age will rise to 75 for individuals who turn 73 after December 31, 2032.13Congress.gov. Required Minimum Distribution (RMD) Rules for Original Owners
Qualified Joint and Survivor Annuity
Any plan that pays benefits as a life annuity must offer a qualified joint and survivor annuity (QJSA) as the default payment method. The QJSA pays a reduced benefit during the participant’s lifetime, then continues paying a portion to a surviving spouse.14eCFR. 26 CFR 11.401(a)-11 – Qualified Joint and Survivor Annuities A participant can opt out only with spousal consent. The requirement most often affects defined benefit pensions, but reaches any plan that offers an annuity option.
Anti-Alienation
Section 401(a)(13) generally prohibits plan benefits from being assigned, garnished, or attached by creditors. The protection extends through bankruptcy and most civil judgments.15eCFR. 26 CFR 1.401(a)-13 – Assignment or Alienation of Benefits Narrow exceptions exist: a qualified domestic relations order (QDRO) can divide a benefit in divorce, the IRS can levy plan assets for unpaid federal taxes, and a participant can voluntarily pledge a portion of their benefit to repay a plan loan.
Top-Heavy Rules
Section 416 adds extra requirements when a plan becomes top-heavy, meaning more than 60% of total plan assets sit in accounts belonging to key employees, generally owners and officers above certain compensation thresholds.16Internal Revenue Service. Questions and Answers on Top-Heavy Plans This shows up often in small businesses where a few owners and highly paid executives dominate the balances.
A top-heavy defined contribution plan must provide each non-key employee with a minimum contribution of at least 3% of compensation for the year, whether or not those employees defer any of their own pay.17Internal Revenue Service. Top-Heavy Errors in Defined Contribution Plans The employee’s own elective deferrals don’t count toward that 3%. A safe harbor plan that already delivers a 3% nonelective contribution generally satisfies the top-heavy minimum automatically.
Staying Qualified After Adoption
Qualification is not a one-time event. Ongoing reporting and prompt correction of operational mistakes are part of what keeps the plan compliant.
Form 5500
Most ERISA-covered qualified plans must file Form 5500 annually, reporting on the plan’s financial condition, investments, and operations. The deadline is the last day of the seventh month after the plan year ends, which lands on July 31 for calendar-year plans.18Internal Revenue Service. Form 5500 Corner Late filings carry penalties of $250 per day, up to $150,000 per return, plus interest, with an additional $1,000 penalty for a late actuarial report on a defined benefit plan.19Internal Revenue Service. Penalty Relief Program for Form 5500-EZ Late Filers
Fixing Errors
The IRS Employee Plans Compliance Resolution System (EPCRS) lets plan sponsors correct operational mistakes without losing qualified status. Common errors like accidentally excluding an eligible employee or miscalculating a contribution can often be self-corrected without paperwork or a fee, provided the plan had reasonable procedures in place and the failure was an oversight rather than a systemic disregard of the rules.20Internal Revenue Service. Retirement Plan Errors Eligible for Self-Correction Insignificant operational failures can be self-corrected at any time; significant failures have a set correction window. Plan document failures, such as missing a required amendment, cannot be self-corrected and require the Voluntary Correction Program.
What Disqualification Costs
Disqualification hits from several directions at once. The plan trust loses its tax-exempt status and owes income tax on its investment earnings. Employer contributions already deducted may be challenged. Participants may owe income tax on employer contributions that were previously tax-deferred. Rollovers out of the plan lose their tax-free treatment. That combination is why sponsors invest in annual testing and use EPCRS to fix problems while correction is still available.