Self-Employed · Freelancers · 1099

South Dakota Solo 401(k) Calculator 2026

Your exact contribution limit and combined federal + South Dakota state tax savings. Free, no sign-up.

South Dakota state tax

No State Income Tax

2026 max contribution

$70,000

Est. total savings*

$9,240

Deadline to open

Dec 31, 2026

*Based on $42,000 contribution at 22% federal + 0% state rate

South Dakota tax note: South Dakota has no state income tax on earned income. As a self-employed South Dakota resident, your Solo 401(k) tax savings come entirely from federal income taxes — but at 22–24% marginal rates, that's still thousands of dollars per year on a meaningful contribution.

Your situation

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✦ Import from document

Paste an offer letter, 1099, contract, or any document with income details — Claude will fill the fields for you.

Affects catch-up contribution limits (age 50+, 60–63 enhanced)

From Schedule C line 31, or your best estimate if mid-year

Enter 0 if you have no day job. Affects IRA deductibility and total 401(k) room.

An HDHP (high-deductible plan) unlocks HSA contributions — the only triple-tax-advantaged account

Traditional IRA, SEP-IRA, or SIMPLE IRA balances. Affects backdoor Roth eligibility.

We never store your inputs. All calculations happen on our server.

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Your 2026 retirement plan

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Solo 401(k) Tax Savings in South Dakota

South Dakota has no state income tax on earned income. As a self-employed South Dakota resident, your Solo 401(k) tax savings come entirely from federal income taxes — but at 22–24% marginal rates, that's still thousands of dollars per year on a meaningful contribution.

While South Dakota residents don't get an additional state tax deduction, the federal savings are still substantial. A self-employed South Dakota resident in the 22% bracket who contributes $42,000 saves $9,240 in federal income taxes this year.

How to open a Solo 401(k) as a South Dakota freelancer

  1. Get an EIN — free at IRS.gov, takes 5 minutes. Required even as a sole proprietor.
  2. Choose a provider — Fidelity, Schwab, and Vanguard offer free Solo 401(k) plans with no annual fees.
  3. Open by December 31 — the account must exist before year-end for contributions to count for that tax year.
  4. Fund by your filing deadline — April 15, 2027, or October 15 with an extension.

Frequently Asked Questions

How much can a self-employed South Dakota resident contribute in 2026?

The 2026 Solo 401(k) limit is $70,000 ($77,500 with catch-up for those 50+). Your exact maximum depends on your net self-employment income after the SE tax deduction. Use the calculator above for your specific number.

Does South Dakota tax Solo 401(k) contributions?

South Dakota has no state income tax on earned income, so Solo 401(k) contributions only reduce your federal taxable income. Your savings are still significant at 22–37% federal rates.

Solo 401(k) vs. SEP-IRA — which is better for South Dakota freelancers?

For most South Dakota self-employed professionals earning under $280,000, a Solo 401(k) allows larger contributions than a SEP-IRA — especially at income under $120,000. Both receive the same South Dakota state tax treatment on contributions.

When is the Solo 401(k) deadline for South Dakota residents?

The account must be open by December 31, 2026. Employee deferrals are elected by year-end. Employer contributions can be made up to your tax filing deadline — April 15, 2027, or October 15 with an extension.

Solo 401(k) guides by state

All states →North DakotaNebraskaMinnesota

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