Self-Employed · Retirement

Solo 401(k) for Software Developers — 2026 Calculator

Freelance and contract software developers are among the highest earners in the self-employed world. A Solo 401(k) is often the single most powerful tax tool available — sheltering up to $70,000 per year.

2026 max contribution

$70,000

Typical income range

$100,000–$350,000

Catch-up (age 50+)

+$7,500

Deadline to open

Dec 31, 2026

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) for Software Developers: What You Need to Know

Business structure

Most freelance developers file Schedule C or operate as a single-member LLC. At $120,000+ in net income, S-Corp election (LLC taxed as S-Corp) can save $8,000–$15,000 annually in SE taxes on top of the 401(k) deduction.

Income pattern & timing

Contract dev work often comes in 3–12 month engagements. Between contracts, contribute conservatively. In high-income periods, front-load employee deferrals since the $23,500 limit is calendar-year based.

Key strategy

Software developers frequently overlook that stock options and RSUs from a primary employer don't count as self-employment income. Only contract/1099 income feeds your Solo 401(k) contribution calculation.

Solo 401(k) vs. SEP-IRA for software developers

A Solo 401(k) allows both an employee deferral (up to $23,500 in 2026) and an employer contribution (up to 25% of net compensation), for a combined maximum of $70,000. A SEP-IRA only allows employer contributions — no employee deferral. This means self-employed software developers earning under approximately $120,000 in net income can typically contribute more to a Solo 401(k) than a SEP-IRA.

How to open a Solo 401(k) as a software developer

  1. Get an EIN (free at IRS.gov, takes 5 minutes online). You need this even as a sole proprietor.
  2. Choose a provider. Fidelity, Schwab, and Vanguard offer free Solo 401(k) plans. Fidelity supports both traditional and Roth contributions with no fees.
  3. Open the account before December 31 of the tax year you want contributions to count.
  4. Fund the account by your tax filing deadline — April 15, or October 15 if you file an extension.

Frequently Asked Questions

Can software developers open a Solo 401(k)?

Yes. Self-employed software developers with Schedule C or 1099 income qualify for a Solo 401(k) as long as they have no full-time W-2 employees other than a spouse. The 2026 contribution limit is $70,000 ($77,500 with catch-up for those 50+).

I have a W-2 job and freelance on the side. How much can I contribute to a Solo 401(k)?

The $23,500 employee deferral limit is shared across all 401(k) plans. If your employer's plan contributes $23,500 already, you can't add employee deferrals to your Solo 401(k). However, the employer contribution (25% of net self-employment income) is completely separate — you can still make that contribution regardless of W-2 plan contributions.

Can I contribute to a Solo 401(k) and an HSA at the same time?

Yes. HSA contributions ($4,300 individual, $8,550 family in 2026) are completely separate from 401(k) limits. Maxing both your Solo 401(k) and HSA is one of the most tax-efficient strategies for self-employed developers — you can shelter $74,300–$78,550 from taxes annually.

Does a Solo 401(k) make sense if I'm saving to buy a house in 2 years?

Carefully — 401(k) funds are locked until 59½ without a 10% penalty (with exceptions). If you need the capital within 5 years, maxing a taxable brokerage or paying off high-interest debt may serve you better. Many developers maintain a Solo 401(k) for long-term retirement savings while keeping shorter-term savings liquid.

Other Solo 401(k) guides

Solo 401(k) calculator →ConsultantsIndependent ContractorsContent Creators

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