"What If" Tax Planner

Decumulation Scenarios — CA + Fed
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Retirement "What If" Tax Planner — CA + Federal Scenarios compared: Just-retired / 1-SS / 2-SS Pre-RMD / RMD Phase  |  MFJ Filing Status  |  California Resident

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

IRMAA impact = Tax Year + 2
ⓘ 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 + 401k Withdrawal


Total Income
Provisional Income
Taxable SS
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 Tier
Surcharge/yr
IRMAA Applies In
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


Total Income
Provisional Income
Taxable SS
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 Tier
Surcharge/yr
IRMAA Applies In
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)


Total Income
Provisional Income
Taxable SS
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 Tier
Surcharge/yr
IRMAA Applies In
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


Total Income
Provisional Income
Taxable SS
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 Tier
Surcharge/yr
IRMAA Applies In
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)

Conversion Range
$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
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
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