Tax · 7 min read

SEP IRA vs Solo 401(k)

Freelancers can shelter more income from tax than almost any W-2 employee — but only if they pick the right retirement plan. SEP IRA and Solo 401(k) are the two workhorses.

How each plan works

  • SEP IRA — employer-only contributions, up to 25% of net self-employment income, simple to open and run
  • Solo 401(k) — employee + employer contributions, available to owner-only businesses (plus spouse), supports Roth + loans

Contribution limit shape

  • Both plans share a high overall cap (indexed annually — check current year)
  • Solo 401(k) usually lets lower-income freelancers contribute more because of the employee deferral
  • SEP usually catches up at higher income because the 25% employer side dominates

Roth and loan features

  • Solo 401(k) supports Roth deferrals (Solo Roth 401(k))
  • Solo 401(k) supports participant loans up to plan limits
  • SEP IRA is traditional pre-tax only and has no loans
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Setup and deadlines

  • SEP — can be opened and funded up to your tax filing deadline (including extensions)
  • Solo 401(k) — plan must generally be established by December 31; funding deadlines vary by source
  • Both require an EIN to open

When each plan wins

  • Lower or mid-five-figure profit — Solo 401(k) usually contributes more
  • High six-figure profit — SEP and Solo 401(k) converge near the overall cap
  • Want Roth or a loan option — Solo 401(k)
  • Want minimum paperwork and late setup — SEP IRA

Frequently asked

Can I have both a SEP and a Solo 401(k)?

Technically yes, but they share the overall contribution limit and most freelancers gain nothing by stacking them. Pick one.

What if I hire employees later?

Solo 401(k) is owner-only — adding non-spouse employees forces conversion to a regular 401(k). SEP IRA must cover eligible employees on the same percentage you contribute for yourself.

Recommended next step

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