Roth Conversion Planner – Low‑Income Year

Roth Conversion Planner

Model a Roth conversion during a low‑income year. Baseline vs With‑Conversion — including stacking into brackets, Social Security taxation, NIIT checks, and ACA/IRMAA risk flags. No data stored.

Household

Filing status

Dependents

Taxpayer age

Spouse age (if MFJ)

State

State tax mode

Flat state rate (%)

Household size (ACA)

On ACA marketplace?

On Medicare?

Income (before conversion)

Wages / self‑employment

Ordinary interest

Qualified dividends

Ordinary dividends

Short‑term capital gains

Long‑term capital gains

Rental / passive

Tax‑exempt interest

Social Security (gross, annual)

If SS > 0, tool applies provisional‑income rules

Deductions

Standard or itemized?

Above‑the‑line (HSA, trad 401k, etc.)

IRA & Conversion

IRA total on Dec 31 (trad/SEP/SIMPLE)

After‑tax IRA basis (prior 8606 line 14)

Planned Roth conversion

Granular what‑if (last $1k)

Advanced config (tax-year parameters)

These are example 2025-ish placeholders. Update annually in production. No external calls; copy current values here.

Results

Scenario

Baseline (no conversion)

Federal tax

–

State tax

–

SS taxable

–

NIIT

–

ACA status

–

Total tax

–

Scenario

With Conversion

Federal tax

–

State tax

–

SS taxable

–

NIIT

–

ACA status

–

Total tax

–

Delta & Warnings

Δ Total tax

–

Eff. marginal on last $1,000

–

Bracket Fill (Ordinary)

Baseline

With conv

Bar shows share of taxable ordinary income vs. total ordinary brackets used. (LTCG/QD taxed on top using their own brackets.)

Pro‑rata (Form 8606) details

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