Pre-Tax vs Roth
Pre-Tax vs Roth 401(k) modeling with retirement taxes included
Compare traditional and Roth 401(k) contributions with explicit retirement-tax assumptions, sidecar investing, and RMD treatment.
The right answer on pre-tax versus Roth depends on lifetime tax structure, not current versus future brackets alone.
This page covers the modeling inputs: deferrals, sidecar investing, match treatment, Social Security interactions, and RMD behavior.
What the model includes
- Traditional and Roth employee deferrals.
- A taxable sidecar for current-year tax savings.
- Retirement taxes, Social Security taxation, and RMD treatment.
Why generic advice falls short
A traditional-versus-Roth decision changes once you include match treatment, state taxes, Social Security interactions, and the fact that you can invest pretax tax savings elsewhere.
What to focus on
- Current marginal rate versus retirement income mix.
- Employer match structure and contribution limits.
- Whether the model should run in real or nominal dollars.
What to read alongside it
- Tax Rates 2026 for bracket context.
- Compensation Planner when equity comp is part of the plan.
- The full docs for modeling notes and caveats.
FAQ
Does the tool assume the Roth path has no employer match?
No. The tool models employer match as pretax dollars in both paths. That detail matters when you compare after-tax outcomes later in retirement.