"What If" Retirement Tax Planner (CA + Fed)

Retirement "What If" Scenarios - Enter approx values of incomes and see how taxes work out

Tax Year

IRMAA impact = Tax Year + 2

CA Personal Exempt Credit

ⓘ SS excluded from CA income · LTCG at ordinary CA rates
ⓘ IRMAA uses 2-yr lookback — this year's AGI affects premiums in Tax Year + 2

Scenario 1 · Roth Conversion + Stock sale

Roth Conversion

401(k) Withdrawal

SS Annual Income

RMD Amount

Other Income

LT Capital Gains

Fed Std Deduction

CA Itemized Ded

— Income Summary —

Total Income

—

Provisional Income

—

Taxable SS

—

— Federal —

Federal AGI

—

Std Deduction

—

Ord Taxable Inc

—

Fed Ordinary Tax

—

Fed LTCG Tax

—

NIIT (3.8%)

—

Fed Total Tax

—

Marginal Bracket

—

Headroom → Next

—

Fed Eff Rate

—

— IRMAA (Medicare) —

IRMAA Tier

—

Surcharge/yr

—

IRMAA Applies In

—

— California —

CA Adj Income

—

CA Itemized Ded

—

CA Taxable Inc

—

CA Tax (Gross)

—

Exempt Credit

—

CA Tax (Net)

—

CA Marginal

—

CA Eff Rate

—

Total Tax (Fed + CA)

—

Net Take-Home

—

Scenario 2 · Roth Conversion + 1 SS Income

Roth Conversion

401(k) Withdrawal

SS Annual Income

RMD Amount

Other Income

LT Capital Gains

Fed Std Deduction

CA Itemized Ded

— Income Summary —

Total Income

—

Provisional Income

—

Taxable SS

—

— Federal —

Federal AGI

—

Std Deduction

—

Ord Taxable Inc

—

Fed Ordinary Tax

—

Fed LTCG Tax

—

NIIT (3.8%)

—

Fed Total Tax

—

Marginal Bracket

—

Headroom → Next

—

Fed Eff Rate

—

— IRMAA (Medicare) —

IRMAA Tier

—

Surcharge/yr

—

IRMAA Applies In

—

— California —

CA Adj Income

—

CA Itemized Ded

—

CA Taxable Inc

—

CA Tax (Gross)

—

Exempt Credit

—

CA Tax (Net)

—

CA Marginal

—

CA Eff Rate

—

Total Tax (Fed + CA)

—

Net Take-Home

—

Scenario 3 · Roth Conversion + 2 SS (Pre-RMD)

Roth Conversion

401(k) Withdrawal

SS Annual Income

RMD Amount

Other Income

LT Capital Gains

Fed Std Deduction

CA Itemized Ded

— Income Summary —

Total Income

—

Provisional Income

—

Taxable SS

—

— Federal —

Federal AGI

—

Std Deduction

—

Ord Taxable Inc

—

Fed Ordinary Tax

—

Fed LTCG Tax

—

NIIT (3.8%)

—

Fed Total Tax

—

Marginal Bracket

—

Headroom → Next

—

Fed Eff Rate

—

— IRMAA (Medicare) —

IRMAA Tier

—

Surcharge/yr

—

IRMAA Applies In

—

— California —

CA Adj Income

—

CA Itemized Ded

—

CA Taxable Inc

—

CA Tax (Gross)

—

Exempt Credit

—

CA Tax (Net)

—

CA Marginal

—

CA Eff Rate

—

Total Tax (Fed + CA)

—

Net Take-Home

—

Scenario 4 · RMD + 2 SS Incomes

Roth Conversion

401(k) Withdrawal

SS Annual Income

RMD Amount

Other Income

LT Capital Gains

Fed Std Deduction

CA Itemized Ded

— Income Summary —

Total Income

—

Provisional Income

—

Taxable SS

—

— Federal —

Federal AGI

—

Std Deduction

—

Ord Taxable Inc

—

Fed Ordinary Tax

—

Fed LTCG Tax

—

NIIT (3.8%)

—

Fed Total Tax

—

Marginal Bracket

—

Headroom → Next

—

Fed Eff Rate

—

— IRMAA (Medicare) —

IRMAA Tier

—

Surcharge/yr

—

IRMAA Applies In

—

— California —

CA Adj Income

—

CA Itemized Ded

—

CA Taxable Inc

—

CA Tax (Gross)

—

Exempt Credit

—

CA Tax (Net)

—

CA Marginal

—

CA Eff Rate

—

Total Tax (Fed + CA)

—

Net Take-Home

—

Tax Breakdown by Scenario

🔍 Roth Conversion Optimizer — Find the Sweet Spot

Base Income (non-conversion sources)

SS Income

RMD

401(k) Withdrawal

Other Income

LT Capital Gains

Fed Std Deduction

CA Itemized Ded

Conversion Range

Max Conversion ($)

Conversion → $100,000

        ⓘ Vertical dashed lines = federal bracket boundaries & IRMAA thresholds

        ⓘ Gold line = total tax (Fed+CA). Blue line = IRMAA annual surcharge (couple).

        ⓘ Optimal conversion fills your current bracket without crossing into the next.

⚖️ Break-Even Roth Conversion Analysis

Conversion Parameters

Conversion Amount ($)

Tax Rate Paid Now (%)

Future RMD Rate (%)

Investment Return (%)

Taxable Acct Return (%)

Project Years

Run calculation…

        ⓘ Green = cumulative Roth advantage (after upfront tax opportunity cost).

        ⓘ Break-even = year the line crosses zero. Positive = Roth ahead, Negative = traditional still better.

        ⓘ Opportunity cost = upfront tax amount invested in taxable account at "Taxable Acct Return".

Tax Engine — Key Rules ✓ Federal brackets: 2026 MFJ projected · SS taxability: full IRS two-tier worksheet ($32k/$44k PI thresholds) · LTCG: preferential rates (0/15/20%) stacked on ordinary taxable income · NIIT: 3.8% on investment income when MAGI > $250k (MFJ) · IRMAA: 2025 MFJ brackets, 2-year lookback (this year's AGI → Medicare premiums in Tax Year + 2) · California: SS fully excluded · LTCG at ordinary CA rates · 10 CA brackets · effective rates on AGI

	👍 Yes	😐 Sort of	👎 No
Content was easy to understand
I found what I was looking for
Calculators were helpful & accurate
I'd recommend this site to a friend