Solo 401(k) Contribution Planning Guide

Estimate self-employed Solo 401(k) contribution scenarios, compare pre-tax and Roth choices, and build a setup checklist with CPA questions.

Prompt Template

Act as a financial planning educator for self-employed professionals. Create a Solo 401(k) contribution planning guide for [person/business] for tax year [year].

Business type/entity: [sole proprietor/LLC/S-corp/etc.]
Age: [age]
Estimated net self-employment income or W-2 wages from the business: [income]
Existing retirement contributions this year: [401k/IRA/SEP/etc.]
Employees other than owner/spouse: [yes/no]
Cash flow available for retirement savings: [monthly/annual amount]
Pre-tax vs Roth preference: [preference/unknown]
Tax bracket estimate: [estimate if known]
CPA/payroll setup: [details]

Provide:
1. **Eligibility check** — owner-only/spouse-only rule and employee caveats
2. **Contribution estimate** — employee deferral, employer contribution, catch-up if applicable, and total range
3. **Pre-tax vs Roth decision framework**
4. **Cash-flow funding schedule** — monthly/quarterly/year-end options
5. **Setup checklist** — provider selection, plan documents, payroll coordination, bank transfers
6. **Deadline checklist** — establishment, employee deferral election, employer contribution timing
7. **Tax reporting notes** — what to confirm with a CPA
8. **Scenario table** — conservative, target, and max contribution cases
9. **Questions for CPA/advisor**

Include a clear disclaimer that contribution limits and calculations depend on tax law, entity type, and compensation details, so the user should verify with a qualified tax professional.

Example Output

Eligibility Check

Assuming the business has no eligible employees other than the owner, a Solo 401(k) may be an option. If part-time employees meet eligibility rules, confirm plan requirements with a benefits professional before proceeding.

Scenario Table

| Scenario | Employee Deferral | Employer Contribution | Total | Notes |

|---|---:|---:|---:|---|

| Conservative | $12,000 | $3,000 | $15,000 | Fits current cash reserve goal |

| Target | $18,000 | $6,000 | $24,000 | Requires quarterly transfers |

| Max estimate | Verify with CPA | Verify with CPA | TBD | Depends on final net income and annual IRS limits |

CPA Questions

1. Based on my entity type, what compensation number should employer contribution be calculated from?

2. Should I use Roth, pre-tax, or split contributions this year?

3. What plan setup deadline applies for tax year 2026?

Tips for Best Results

  • 💡Provide entity type and compensation details; Solo 401(k) math changes by structure.
  • 💡Ask for scenarios instead of one exact answer if income is variable.
  • 💡Have the model generate CPA questions so you can verify before moving money.
  • 💡Do not treat the output as tax advice; contribution limits and deadlines change.