Roth conversion optimizer
Should they convert before RMDs and IRMAA hit? Fill the 24% bracket each year to retirement and compare lifetime after-tax wealth against doing nothing.
1 · Make the call
Send the balances, target bracket, and conversion window to
/v1/roth-conversion.
curl -X POST https://api.numeratica.com/v1/roth-conversion \
-H "Authorization: Bearer nmr_sk_test_xxx" \
-H "Content-Type: application/json" \
-d '{
"tax_year": 2026, "filing_status": "mfj",
"current_age": 63, "end_age": 90, "birth_year": 1963,
"tax_deferred_balance": 1500000, "roth_balance": 100000,
"other_ordinary_income": 30000, "annual_return": 0.05,
"target_bracket": 0.24, "conversion_end_age": 73, "irmaa_tier_cap": 2
}'2 · The response
A year-by-year schedule (conversion, tax, IRMAA tier, balances)
plus the lifetime comparison. The headline is after_tax_value_gain.
{
"result_id": "roth_149f95cd3551cb3f",
"engine_version": "roth-conversion-1.0.0",
"result": {
"schedule": [ /* one row per year: age, conversion, tax, irmaa_tier, roth_end, ... */ ],
"with_conversions": {
"total_converted": 1664225.55,
"total_tax": 309609.62,
"total_irmaa_surcharge": 14424,
"after_tax_ending_value": 5160136.98
},
"baseline": {
"total_tax": 354668.71,
"after_tax_ending_value": 2166364.63
},
"after_tax_value_gain": 2993772.36
},
"disclaimer": "Calculation engine output for informational purposes only; not tax or financial advice."
}3 · Render it
Turn the comparison into a recommendation card a client immediately understands.
Rendered output
<div style="font-family:-apple-system,Segoe UI,Roboto,Helvetica,Arial,sans-serif;max-width:440px;border:1px solid #e6e9ef;border-radius:14px;overflow:hidden;color:#1a2230">
<div style="background:#ecfdf5;padding:16px 20px;border-bottom:1px solid #e6e9ef">
<span style="display:inline-block;background:#047857;color:#fff;font-size:12px;font-weight:700;padding:3px 11px;border-radius:999px;letter-spacing:.04em">✓ CONVERT</span>
<div style="color:#5b6675;font-size:13px;margin-top:12px">Projected lifetime after-tax gain</div>
<div style="font-size:34px;font-weight:700;color:#047857;line-height:1.1">+$2.99M</div>
</div>
<div style="padding:8px 20px 14px;font-size:14px">
<div style="display:flex;justify-content:space-between;padding:7px 0;border-bottom:1px solid #f1f3f7"><span style="color:#5b6675">With conversions</span><strong>$5.16M</strong></div>
<div style="display:flex;justify-content:space-between;padding:7px 0;border-bottom:1px solid #f1f3f7"><span style="color:#5b6675">Baseline (no conversions)</span><strong>$2.17M</strong></div>
<div style="display:flex;justify-content:space-between;padding:7px 0;border-bottom:1px solid #f1f3f7"><span style="color:#5b6675">Total converted</span><strong>$1.66M</strong></div>
<div style="display:flex;justify-content:space-between;padding:7px 0;border-bottom:1px solid #f1f3f7"><span style="color:#5b6675">Conversion tax</span><strong>$309,610</strong></div>
<div style="display:flex;justify-content:space-between;padding:7px 0"><span style="color:#5b6675">Extra IRMAA surcharge</span><strong>$14,424</strong></div>
</div>
<div style="padding:10px 20px;color:#9aa3b0;font-size:11px;border-top:1px solid #f1f3f7">Fill the 24% bracket through age 73 · result_id roth_149f95cd3551cb3f · not tax advice</div>
</div>