W-2 salary (from Step 1) drives the retirement contribution calculation. Employer contributions (Solo 401(k), SEP, DB Plan, Cash Balance) are calculated as a % of W-2 compensation.
Solo 401(k) 2025: $23,500 employee deferral + 25% of W-2 as employer match = up to $70,000 total ($77,500 if age 50+, $73,500 if 60-63 super catch-up).
Defined Benefit / Cash Balance plans allow significantly larger deductible contributions based on actuarial calculations — but require W-2 wages as the base.
⚠ If salary is set too low, retirement contributions are also capped lower. This is a key tension in salary planning — balance SE tax savings vs. retirement funding.