SIMPLE IRA vs. SEP IRA for a Small Business: What's the Difference?
A small business owner setting up a retirement plan for the first time often narrows the field to two options built specifically for smaller employers — and the difference between them comes down mostly to who can contribute what.
The short answer
A SIMPLE IRA and a SEP IRA are both retirement plans designed for small businesses, but they differ in a key way: a SIMPLE IRA allows employees to contribute their own money from each paycheck, while a SEP IRA is funded entirely by employer contributions. That single distinction shapes almost everything else about how the two plans are administered and who tends to prefer each one.
Who can contribute
With a SIMPLE IRA, eligible employees can choose to defer part of their own pay into the account, and the employer generally adds a contribution on top, using one of a small number of set formulas. With a SEP IRA, employees don’t contribute anything themselves — the employer decides each year whether and how much to contribute, calculated as a percentage of each eligible employee’s pay, including the owner’s own compensation if self-employed.
Employer contribution rules
Both plans require the employer to contribute, but the shape of that requirement differs.
- SIMPLE IRA. The employer is generally required to make a contribution every year the plan is active, choosing between a small number of predictable contribution formulas, and can’t skip a year simply because business was slow.
- SEP IRA. The employer can generally decide year to year whether to contribute at all, which gives more flexibility in lean years, but if a contribution is made, it must follow a uniform percentage across eligible employees, including the owner.
Administrative simplicity
Both plans are designed to be lighter on paperwork than a typical employer 401(k) plan, but there are still differences. A SIMPLE IRA involves ongoing payroll coordination, since employee contributions have to be deducted and forwarded regularly, along with an annual notice to employees about their right to participate. A SEP IRA has less ongoing administrative overhead, since there’s no employee deferral to track — the employer simply calculates and deposits its own contribution when it chooses to make one.
What tends to influence the choice
A small business with employees who want to save through payroll deductions, and an owner comfortable with a required annual contribution, may lean toward a SIMPLE IRA. A business owner who wants maximum flexibility about whether to contribute in a given year, and who isn’t as focused on giving employees a payroll-deduction savings option, may lean toward a SEP IRA instead. Business size, cash flow predictability, and how much the owner wants employees actively participating all factor into the decision.
What to weigh
Because contribution formulas, deadlines, and eligibility rules for both plan types are set by the government and can change over time, the details are worth confirming against current guidance before adopting either one. The core distinction, though, tends to hold steady: a SIMPLE IRA is built around employee deferrals plus a required employer piece, while a SEP IRA is built entirely around a flexible, employer-only contribution.