Retirement Tax Optimizer
A mobile-first PWA that helps a couple approaching retirement figure out
which accounts to withdraw from, in what order, to pay as little federal tax
as possible — across rollover 401(k)s, Traditional IRAs, Roth IRAs, a taxable
brokerage, cash, and Social Security — filing jointly or single (the survivor model files single), with work income for still-working households.
It models the real, interacting tax rules retirees face: ordinary brackets,
the taxability of Social Security, long-term capital-gains rates, Required
Minimum Distributions (RMDs), the Medicare IRMAA surcharge cliffs, and the Net
Investment Income Tax — using 2026 figures.
⚠️ Educational estimates only — not tax, legal, or investment advice.
Federal + Illinois state tax (IL exempts retirement income; wages and investment income are taxed). Verify with a qualified professional.
What it does
- Setup (
/) — a short, one-question-at-a-time walkthrough that builds the
plan, ending on your first three moves. Returning users land on the Plan tab;
the Setup tab then lists every answer, each one tap from where it's changed.
- This year's plan (
/plan) — action-first: what to do (which named
account each dollar comes from, deadlines, "I did this"), what's coming up
(tax dates, Social Security, Medicare, RMDs), why (one short card per
decision), then the detail collapsed. Given your spending target, it picks the
withdrawal mix (pre-tax → brokerage → Roth) that minimizes tax, always taking
required RMDs first. Shows a source donut, the full income/tax breakdown,
effective & marginal rates, SS taxability, capital-gains rate, NIIT, and the
IRMAA tier. Switch strategies (smart bracket-fill / conventional /
proportional) and pick the bracket to fill.
- Quarterly review PDF (
/report) — the whole plan written up like an
advisor's report (≈13–19 letter pages): executive summary and recommendations,
this quarter's deadlines, the year's custodian-ready action plan, portfolio and
every holding, withdrawal and Roth-conversion strategy, Social Security, taxes
and Medicare, Monte-Carlo outlook and stress tests, a year-by-year appendix.
Each quarter's report compares against the last one. Saved via the browser's
print dialog; made on-device.
- Opportunities — actionable, sourced callouts: Roth-conversion headroom in
low-tax years, 0% capital-gains harvesting, IRMAA-cliff avoidance, QCDs once
RMD-eligible, the pre-tax "RMD tax bomb," and asset-location tips.
- Lifetime forecast (
/projection) — a 20–30+ year, year-by-year
projection with market-return scenarios (conservative / moderate /
optimistic), inflation, and horizon controls. Charts the balance of each tax
bucket over time, the RMD ramp, and smart vs. conventional lifetime tax.
- Key decisions & milestones — flags the years the strategy has to change:
the low-tax conversion window, Social Security claim years, RMD start, bracket
step-ups, when Roth gets tapped, and any shortfall.
- Learn (
/learn) — plain-English explanations of every rule, each with a
link to the authoritative IRS / SSA / Medicare source.
- Built-in $5M example — a ready-made household (~$5M across every account
type), with each account broken out into realistic holdings (stocks,
ETFs, mutual funds) showing shares, price, value, and cost basis. Your own
inputs persist on-device (localStorage); nothing is uploaded.
Stack
- Next.js 16 (App Router) + React 19 + TypeScript
- Tailwind v4 — light-mode-only theme tokens (deep slate-teal brand, gold
accent, semantic money colors) as CSS variables via
@theme in
app/globals.css
- Dependency-free SVG charts (donut, stacked area, bars, animated count-ups)
in
components/charts.tsx
- PWA — standalone manifest; deploys to Vercel out of the box
Quick start
npm install # .npmrc sets legacy-peer-deps
npm run dev # http://localhost:3000
npm run build # production build (all routes static)
npm run typecheck
How the engine is organized
Key tax facts baked in (2026)
- RMDs apply only to pre-tax accounts, starting at age 73 (born
1951–1959) or 75 (born 1960+) under SECURE 2.0. Roth IRAs have no
lifetime RMDs — a common misconception is that they do; the planner spends
Roth last for exactly this reason.
- Up to 85% of Social Security can be taxable based on provisional income.
- Long-term gains/qualified dividends get 0% / 15% / 20% rates, stacked on
top of ordinary income.
- The 2025–2028 senior bonus deduction and the age-65 additional standard
deduction are both modeled (with phaseouts).
Update the numbers each year in lib/tax/constants.ts.
