Small business
SEP vs. SIMPLE vs. 401(k): Picking Vocabulary for Your Business Size
Searches like SEP vs 401k or SIMPLE IRA vs 401k come from owners comparing low-administration IRAs to full 401(k) plans. SEP IRAs are predominantly employer-funded. SIMPLE IRAs combine employee salary deferral with required employer contributions under a lighter framework than many 401(k)s. 401(k) plans offer maximum design flexibility—and compliance complexity.
Definitions & sponsor goals
SEP (IRA-based)
Employer contributions to individual IRAs—relatively simple paperwork, flexible contribution percentages within IRS rules, but employee deferrals are not part of classic SEP mechanics.
SIMPLE IRA
Smaller employers may use SIMPLE with employee salary reductions plus required employer match or nonelective contributions—lighter than many 401(k)s but with its own limits and timelines.
401(k)
Supports elective deferrals, match/profit sharing, Roth, loans (if adopted), and richer designs— with testing and fiduciary duties scaled to complexity.
Rule highlights (owner decision factors)
Solo and one-participant 401(k)
Self-employed readers should start with solo 401(k) and compare to SEP contribution mechanics for high self-employment income.
W-2 workforce considerations
Once you hire non-owner staff, nondiscrimination, coverage, and eligibility rules weigh heavily— a TPA should model scenarios.
How this connects to our calculators
W-2 education tools
Our 401k calculators assume W-2-style salary patterns for education—not self-employment net earnings rules.
Limits context
Compare statutory ceilings on our limits page with SEP/SIMPLE-specific caps in IRS materials—do not mix tables blindly.
Common misconceptions
“SEP is always cheapest”
Contribution patterns and employee growth can flip total cost vs. a well-run safe harbor 401(k).
“We can switch plans every January without consequences”
Mid-year plan changes can trigger notice requirements and employee protections—plan ahead.
Administrative load: what owners actually do
SEP paperwork
SEP contributions go to IRAs—fewer payroll features than a 401(k), but owners must still track eligibility, compensation, and contribution percentages within IRS limits each year.
SIMPLE notification rules
SIMPLE plans require annual notices about deferral percentages and employer contributions—missing deadlines can disqualify the plan year.
401(k) fiduciary duties
Full 401(k) plans involve fund selection, fee monitoring, and Form 5500 filings—often outsourced to TPAs but still sponsor responsibilities.
FAQ
Can employees have both SEP and 401(k)?
Combinations interact with annual additions limits—professional setup required.
Where do IRAs fit?
See IRA vs. 401(k) for participant-level vocabulary.
Which plan is better for hiring in the next 12 months?
If you expect to cross SIMPLE or SEP employee limits or need auto enrollment, model 401(k) costs now—retrofits can be expensive.
Checklist: sponsor conversation starters
- Count current and forecast headcount (owners vs. staff).
- List must-have features: Roth, loans, auto enrollment, profit sharing.
- Request three-year cost projections from TPAs for SEP, SIMPLE, and 401(k).