SEP IRA / Solo 401(k) (2026)

Self-employed retirement plan choice

Schedule C filers and independent contractors often choose between SEP-IRAs and Solo 401(k) plans (individual 401(k)). SEP allows employer contributions up to roughly 25% of net self-employment earnings (with compensation definition adjustments). Solo 401(k) adds employee elective deferrals up to $24,500 in 2026 plus employer profit-sharing—often higher total capacity for the same net income.

2026 limits

For 2026, the IRA contribution limit is $7,500 with a $1,100 catch-up at age 50 and older. Elective deferrals to 401(k), 403(b), and most workplace plans cap at $24,500, with catch-up contributions of $8,000 at age 50+ and an enhanced $11,250 catch-up for ages 60 through 63 under SECURE 2.0. HSA limits are $4,400 for self-only HDHP coverage and $8,750 for family coverage, plus a $1,000 catch-up at 55+. Social Security wages for payroll tax purposes stop at the $184,500 wage base (SSA 2026).

Self-employment tax uses net earnings subject to SE tax; SEP/solo employer contributions reduce net profit. Social Security wage base $184,500 affects SE tax, not SEP percentage directly.

Solo 401(k) advantages

• Employee deferral up to $24,500 plus catch-up
• Roth Solo 401(k) deferral if plan document allows
• Spousal employee deferral if spouse earns W-2 from the business

SEP advantages

• Simple setup and low admin cost
• Fund by tax filing deadline with extensions
• Uniform percentage for employees if you hire later

Related tools

Self-employment tax calculator, 401(k) calculator, contribution limits maximizer.

Sources

IRS Publication 560; Rev. Proc. 2025-32; SSA wage base 2026.

Documentation and recordkeeping

Keep copies of forms, notices, and account statements that support numbers you enter. IRS audits and state reviews often start with mismatches between third-party reporting and what you claimed. Reconcile calculator outputs to official worksheets before filing.

When to revisit your estimate

Life changes mid-year—marriage, divorce, a move, bonus income, or a new job—can shift brackets, credits, and phaseouts. Rerun the tool when those events occur rather than relying on a January estimate through December.

State and local taxes

This page focuses on federal rules unless noted. Many states piggyback on federal AGI or MAGI definitions but apply their own rates and credits. Pair federal estimates with the state income tax calculator when residency matters.

Professional guidance

Complex returns—AMT, NIIT, multi-state income, business ownership, or large conversions—benefit from a CPA or enrolled agent who can sign the return. Calculators here show the math chain; they do not replace personalized advice or e-file validation.

Methodology on this site

Core 2026 federal brackets, deductions, and payroll limits follow IRS Rev. Proc. 2025-32, SSA wage-base announcements, and CMS Medicare premium tables where applicable. We show assumptions in the result panel when a rule is simplified for education.

Quarterly check-ins

Retirees and self-employed filers should revisit estimates after each quarter when investment income, required distributions, or business profit shifts. Waiting until December limits your options for withholding adjustments and timely estimated payments.

Documentation and recordkeeping

Keep copies of forms, notices, and account statements that support numbers you enter. IRS audits and state reviews often start with mismatches between third-party reporting and what you claimed. Reconcile calculator outputs to official worksheets before filing.

When to revisit your estimate

Life changes mid-year—marriage, divorce, a move, bonus income, or a new job—can shift brackets, credits, and phaseouts. Rerun the tool when those events occur rather than relying on a January estimate through December.

State and local taxes

This page focuses on federal rules unless noted. Many states piggyback on federal AGI or MAGI definitions but apply their own rates and credits. Pair federal estimates with the state income tax calculator when residency matters.

Professional guidance

Complex returns—AMT, NIIT, multi-state income, business ownership, or large conversions—benefit from a CPA or enrolled agent who can sign the return. Calculators here show the math chain; they do not replace personalized advice or e-file validation.

Methodology on this site

Core 2026 federal brackets, deductions, and payroll limits follow IRS Rev. Proc. 2025-32, SSA wage-base announcements, and CMS Medicare premium tables where applicable. We show assumptions in the result panel when a rule is simplified for education.

Quarterly check-ins

Retirees and self-employed filers should revisit estimates after each quarter when investment income, required distributions, or business profit shifts. Waiting until December limits your options for withholding adjustments and timely estimated payments.

Reading official publications

IRS Publications and Instructions often walk through worksheets line by line. When our simplified path differs from a form worksheet, trust the form for filing and use this page for directional planning only.

Calculator directory

Browse related tools from the calculator directory when your question spans credits, payroll, retirement, and investment tax in the same year.

Withholding versus liability

Paycheck withholding and estimated tax payments are cash-flow tools. They are not the same as annual tax liability computed on the return. Use the W-4 withholding calculator and quarterly estimated tax calculator when you need payment timing, not just liability.

Standard deduction reminder

The 2026 standard deduction is $16,100 for single and married filing separately filers, $24,150 for head of household, and $32,200 for married filing jointly (IRS Rev. Proc. 2025-32). Itemized filers must beat those amounts on Schedule A for itemizing to win.

Documentation and recordkeeping

Keep copies of forms, notices, and account statements that support numbers you enter. IRS audits and state reviews often start with mismatches between third-party reporting and what you claimed. Reconcile calculator outputs to official worksheets before filing.

When to revisit your estimate

Life changes mid-year—marriage, divorce, a move, bonus income, or a new job—can shift brackets, credits, and phaseouts. Rerun the tool when those events occur rather than relying on a January estimate through December.