Introduction – What Is IRS Publication 4336?
Small business owners have several retirement plan options, but older businesses sometimes operate under unique, legacy arrangements. One such arrangement is the Salary Reduction Simplified Employee Pension, commonly known as a SARSEP. Sponsoring a SARSEP allows employees to defer pretax dollars from their paychecks into individual retirement accounts, combined with optional employer contributions.
IRS Publication 4336, titled “SARSEP: Salary Reduction Simplified Employee Pension Plan for Small Businesses,” is an authoritative guide published by the Internal Revenue Service’s Tax Exempt and Government Entities (TE/GE) division. It provides a detailed roadmap for employers who maintain an active, grandfathered SARSEP. The publication explains how these plans operate, who can participate, how contributions are calculated, and what compliance tests must be passed each year.
While the law prohibits business owners from establishing new SARSEPs today, plans created before 1997 can continue to operate indefinitely. Publication 4336 serves as the primary operational manual for employers running these legacy plans, ensuring that they stay fully compliant with federal tax regulations and maintain their tax-exempt status.
Who Should Read This Publication?
Publication 4336 is written for business owners, corporate managers, and employee benefits professionals who oversee an active SARSEP. It explains the administrative responsibilities required to manage this specialized retirement vehicle.
You should review Publication 4336 if you are:
- A Business Owner with a Pre-1997 SARSEP: Employers who adopted a SARSEP before 1997 and continue to fund and administer the plan for their team.
- A Payroll or Human Resources Administrator: Personnel responsible for calculating employee salary reductions, tracking participation percentages, and meeting monthly deposit deadlines.
- A Newly Hired Employee at a Participating Company: Workers joining an established small business who want to understand how their retirement deferrals and company contributions work.
- A CPA, Enrolled Agent, or Plan Consultant: Financial and tax advisors performing annual compliance testing, nondiscrimination reviews, and tax reporting for business clients.
Key Topics Covered in Publication 4336
Publication 4336 covers the ongoing rules and statutory tests needed to operate a SARSEP smoothly. It translates complicated tax code provisions into practical operational steps for small employers.
The primary topics covered within the publication include:
- Grandfathered Status and Size Limits: Understanding why new plans cannot be formed and maintaining the 25-employee ceiling.
- Employee Participation Standards: Determining who must be allowed to join using the statutory three-of-five-year service standard.
- The 50% Participation Mandate: The strict requirement that at least half of all eligible workers must elect to make salary deferrals.
- Annual Nondiscrimination Testing: Applying the 125% Deferral Percentage Test to limit contributions for highly compensated staff.
- Contribution Rules and Deadlines: The differences between employee salary withholdings and discretionary company contributions.
- Top-Heavy Minimum Contributions: Funding requirements when account balances are concentrated among company owners.
| Plan Feature | SARSEP (Publication 4336) | Standard SEP-IRA | SIMPLE IRA |
|---|---|---|---|
| Establishment Status | Grandfathered (pre-1997 only) | Open to new plans | Open to new plans |
| Employee Deferrals | Permitted (pretax salary reductions) | Not permitted (employer-funded only) | Permitted (pretax salary reductions) |
| Employer Size Limit | 25 or fewer eligible employees | No employee limit | 100 or fewer employees |
| Participation Requirement | At least 50% of eligible staff must defer | None (employer-funded) | None (individual choice) |
| Annual Testing | Mandatory 125% ADP test for owners | None required | None required |
Detailed Breakdown of Main Concepts
1. Grandfathered Status and the 25-Employee Ceiling
Under the Small Business Job Protection Act of 1996, Congress prohibited the formation of new SARSEPs after December 31, 1996, replacing them with SIMPLE IRA plans. However, Congress included a grandfather clause allowing existing SARSEPs to remain active. Employers who established a SARSEP before 1997 can keep operating the plan, and new employees hired today are fully eligible to enroll.
Publication 4336 emphasizes that a sponsoring employer can never have more than 25 eligible employees at any time during the preceding calendar year. If your company expands and has 26 or more eligible workers in the prior year, the plan cannot accept employee salary reductions for the current year. When a business outgrows this cap, the employer must look into alternative plans, such as a 401(k) or SIMPLE IRA.
2. The Mandatory 50% Participation Rule
In a standard 401(k) or SIMPLE IRA, each worker decides whether to save for retirement independently. A SARSEP operates under a collective participation standard. In any calendar year in which salary reductions take place, at least 50% of all eligible employees must actually choose to defer part of their pay into the plan.
For example, if a business has ten eligible employees, at least five must elect to make salary reductions. If only four choose to contribute, the plan fails the 50% rule for that year. In that scenario, no one—including the business owner—is allowed to make salary deferrals, and any money withheld must be returned to the employees as taxable wages.
3. The 125% Deferral Percentage Test
To prevent business owners and highly paid staff from using the plan disproportionately for tax sheltering, Publication 4336 outlines an annual nondiscrimination test. Under this rule, the deferral percentage of each Highly Compensated Employee (HCE) cannot exceed 125% of the average deferral percentage of all eligible Non-Highly Compensated Employees (NHCEs).
An HCE generally includes business owners, partners, and employees earning above annual federal compensation limits. If the eligible non-highly compensated group defers an average of 4% of their pay, no highly compensated employee can defer more than 5% (4% multiplied by 1.25). If an owner defers more than this cap allows, the excess contributions must be calculated, distributed back to the owner, and reported as taxable income.
4. Employee Deferrals vs. Discretionary Employer Contributions
A SARSEP accommodates two distinct types of funding: employee salary deferrals and employer non-elective contributions. Employee salary deferrals represent pretax money deducted directly from worker paychecks, subject to annual federal elective deferral limits, with additional catch-up contributions allowed for workers age 50 and older.
In addition to employee deferrals, the employer can choose to make discretionary non-elective contributions. If the employer decides to contribute company funds, the contribution must represent a uniform percentage of compensation across all eligible participants. Employers cannot selectively reward specific managers while excluding other workers.
5. Strict Deposit Timelines: The 15-Day Rule
Because employee salary deferrals represent earned wages withheld from worker paychecks, federal law enforces strict deposit schedules. Publication 4336 warns employers that delayed deposits are treated as prohibited transactions subject to excise penalties.
Employers must deposit employee elective deferrals into participant SEP-IRAs as soon as the funds can reasonably be segregated from general business assets. By law, this must happen no later than 15 days following the end of the month in which the money was withheld from the paycheck. In contrast, company employer contributions can wait until the due date of the business’s federal income tax return, including official extensions.
6. 100% Immediate Vesting and Top-Heavy Rules
All contributions made to a SARSEP—both employee salary deferrals and company contributions—are 100% vested immediately. The funds belong entirely to the employee from the day they are deposited, and employers cannot enforce multi-year vesting schedules or reclaim money if a worker leaves the company.
Furthermore, because SARSEPs are small business plans, they are frequently classified as top-heavy. A plan is top-heavy when more than 60% of total account balances belong to key employees, such as owners and corporate officers. When a plan is top-heavy, the employer must generally provide a minimum contribution—typically up to 3% of compensation—to all eligible non-key workers.
Practical Scenarios Illustrating SARSEP Operations
Scenario 1: Meeting the 50% Participation Threshold
A precision machining company established a SARSEP in 1993. The business currently employs eight eligible workers: the owner, the shop foreman, and six machine operators. When open enrollment begins, the owner, the foreman, and two operators submit salary reduction agreements.
The company accountant reviews the numbers: four out of eight eligible workers (exactly 50%) have elected to contribute. Because the plan reaches the 50% threshold, all salary reductions are valid. Had only three workers participated (37.5%), the plan would have failed, and all salary deferrals would have been canceled for that year.
Scenario 2: Correcting an Excess Deferral Under the 125% Test
A small commercial photography studio operates a grandfathered SARSEP with three eligible workers: the owner and two studio assistants. The owner earns $120,000 and attempts to contribute the maximum federal elective deferral. The two assistants participate, but each defers only 2% of their earnings.
At year-end, the accountant calculates the average deferral rate for the non-highly compensated staff, which is 2%. Under the 125% test, the owner’s deferral rate cannot exceed 2.5% of her salary (2% multiplied by 1.25), which equals $3,000. Following Publication 4336 guidelines, the studio distributes the excess deferral back to the owner before the tax deadline to keep the plan compliant.
How Publication 4336 Relates to Specific IRS Forms
Operating a compliant SARSEP involves several key tax forms and foundational documents referenced throughout Publication 4336:
- Form 5305A-SEP (Salary Reduction Simplified Employee Pension – Individual Retirement Accounts Contribution Agreement): The official IRS model plan document used by employers to establish and operate a SARSEP. Employers must keep an updated, signed copy with company records.
- Form W-2 (Wage and Tax Statement): Elective employee salary deferrals are reported in Box 12 using Code D, and the “Retirement plan” checkbox in Box 13 must be marked.
- Form 5329 (Additional Taxes on Qualified Plans): Filed by participants to calculate and pay penalties if excess deferrals or unallowable contributions remain in an account past legal deadlines.
- Form 5330 (Return of Excise Taxes Related to Employee Benefit Plans): Used by employers to calculate and pay excise taxes if employee salary withholdings are deposited late.
- Business Tax Returns (Forms 1040, 1065, 1120, or 1120-S): The federal returns on which employers report and deduct their discretionary company contributions.
Common Misunderstandings Clarified
- Misunderstanding: A new startup can establish a SARSEP today if it has fewer than 25 employees.
Reality: Federal law prohibited the creation of new SARSEPs after December 31, 1996. Only plans established before 1997 can operate today. - Misunderstanding: New employees hired today cannot participate in a grandfathered SARSEP.
Reality: Any eligible employee hired today can—and must—be allowed to participate in an active grandfathered plan once they meet the statutory age and service requirements. - Misunderstanding: Business owners can always contribute the maximum legal deferral limit.
Reality: Highly compensated employees are constrained by the 125% test. If rank-and-file employees do not contribute, owners cannot defer money either. - Misunderstanding: Employee salary deferrals can wait until company taxes are filed.
Reality: Only employer non-elective contributions can wait until the tax filing deadline. Employee salary deferrals must be deposited no later than 15 days following the month of withholding. - Misunderstanding: Sponsoring a SARSEP requires filing an annual Form 5500.
Reality: Model SARSEPs established using Form 5305A-SEP are generally exempt from annual Form 5500 reporting, saving small businesses significant administrative costs.
Why Publication 4336 Matters for Taxpayers
Maintaining a grandfathered SARSEP offers small businesses a rare advantage: the ability to offer employee salary deferrals with the simple paperwork of an IRA-based plan. However, because SARSEPs are uncommon legacy plans, third-party administrators and payroll providers frequently overlook their unique testing rules.
Publication 4336 matters because it provides the official operating standards needed to keep these plans alive. By following its guidelines, business owners protect their company tax deductions, safeguard their employees’ retirement savings, and avoid costly compliance penalties or plan disqualification.
Frequently Asked Questions
Can an employer establish a new SARSEP plan today?
No. Federal tax laws ended the creation of new SARSEPs on December 31, 1996. Only businesses that adopted a SARSEP prior to 1997 are legally allowed to continue operating them.
What happens if a SARSEP fails the 50% employee participation test?
If fewer than 50% of all eligible employees choose to make salary deferrals during the year, no salary reductions are permitted for that year. Any money withheld must be returned to workers as taxable salary.
What is the 125% deferral percentage test?
The 125% test is an annual nondiscrimination rule ensuring that the deferral percentage of each highly compensated employee does not exceed 125% of the average deferral percentage of all eligible non-highly compensated workers.
What is the deadline for depositing employee salary deferrals?
Employee salary deferrals must be forwarded to the financial institution as soon as possible, but no later than 15 days following the end of the month in which the wages were withheld.
Do employees own their contributions immediately?
Yes. All contributions made to a SARSEP—both employee salary deferrals and employer contributions—are 100% vested immediately and belong entirely to the employee.
What happens if an employer has more than 25 eligible employees in a year?
If an employer has more than 25 eligible employees at any time during the preceding calendar year, the plan can no longer accept salary reductions. The business must freeze deferrals and transition to another plan, such as a 401(k) or SIMPLE IRA.
Conclusion
IRS Publication 4336 serves as an essential manual for the dedicated group of small business owners who continue to maintain grandfathered SARSEP retirement plans. By combining employee pretax salary reductions with the low administrative costs of an IRA, a SARSEP remains an effective benefits tool when operated correctly.
Success with a SARSEP requires careful attention to its unique rules: monitoring the 25-employee ceiling, verifying that at least 50% of staff participate, passing the annual 125% nondiscrimination test, and depositing withholdings within 15 days. By following the guidance in Publication 4336, employers can confidently maintain their plan’s tax-favored standing and support their workforce’s long-term financial security.
