Roth Conversion Planner

• Multi-year Roth conversion schedule with per-owner conversion amounts.
• Baseline and proposed simulations using the same tax profile, accounts, income, return, inflation, and spending assumptions.
• Federal ordinary bracket cap, optional IRMAA tier ceiling, optional ACA percentage-of-FPL ceiling, and optional LTCG 0% and NIIT constraints.
• Roth 5-year-clock handling with hard-block and warn-only policies.
• Per-year cliff distances for IRMAA, ACA, LTCG 0%, and NIIT.
• Year-end account balances and summary deltas for taxes, IRMAA, ACA self-pay costs, and ending wealth.

• Evaluate whether partial Roth conversions can lower lifetime taxes before RMDs, Social Security taxation, Medicare IRMAA, or ACA subsidy cliffs become binding.
• Compare a conversion plan with a no-conversion baseline under one explicit return, inflation, income, and spending path.
• Inspect which tax constraint stops additional conversion capacity in each year.
• Model member ownership, survivor years, Social Security by member, and account subtype differences when conversions are owner-specific.

• Plan anchor: start year and horizon years. Every dated rule is resolved from the explicit start year.
• Tax profile: filing status, members, birth years, optional death years, and optional owner priority.
• Accounts: traditional IRA/401(k), Roth IRA/401(k), HSA, and taxable brokerage balances, with owner IDs and taxable cost basis when relevant.
• Income assumptions: reusable streams for wages, pension, Social Security, and recurring investment income, plus one-time year rows for explicit gains, dividends, or other dated income.
• Assumptions: nominal asset return, inflation rate, and real annual spending.
• Tax tables: federal schedule year, resident state, and state tax year.
• Roth history: optional existing Roth basis, earnings, and first Roth year by member for 5-year-clock handling.
• ACA and IRMAA context: user-added SLCSP premium years, covered members, ACA FPL cap, ACA regime override, and prior MAGI history for the IRMAA lookback.

The planner first simulates a no-conversion baseline. It then builds a proposed schedule one year at a time by filling available conversion capacity until the active constraint set stops additional conversion. Both paths use the same deterministic annual return, inflation, income, spending, tax, and account assumptions.

The simulator models ordinary income, taxable Social Security, RMDs, state tax when a supported state is selected, IRMAA, ACA premium tax credit mechanics, LTCG/NIIT thresholds, Roth basis layers, and same-year tax funding gross-up. Income streams and one-time rows are expanded into a sparse annual request, and missing income years default to zero income rather than inferred values.

• Schedule: conversion amount by year and owner, plus the constraint that stopped the planner at the maximum.
• Yearly rows: baseline and proposed tax bases, conversion amounts, RMDs, tax-funding draws, cliff distances, and end-of-year account balances.
• Summary deltas: proposed minus baseline for ending wealth, federal tax, state tax, IRMAA, and ACA self-pay costs.
• Warnings: table coverage gaps, skipped conversions, clock conflicts, or assumptions that require review.

• Federal and state schedule selectors are limited to the tax years shipped in the backend tables.
• ACA FPL modeling currently supports the contiguous-state table. Alaska and Hawaii tables are not shipped yet.
• The schedule builder is a bracket-fill heuristic. It is not a stochastic or global optimizer.
• Saved analyses for this tool are private-only. Generic public share links are not registered for Roth conversion plans.