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, Qualifying Surviving Spouse years, and Social Security survivor-benefit eligibility, plus 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 tax inputs. Annual rows can include itemized deductions and the SALT portion used for AMT add-back.
• Assumptions: nominal asset return, inflation rate, and real annual spending.
• Tax tables: federal schedule year, resident state, and state tax year.
• Roth history: existing Roth basis, earnings, and first Roth year by member for 5-year-clock handling. If the household has a Roth balance at plan start, the backend requires enough basis and/or earnings detail to classify it.
• ACA and IRMAA context: user-added SLCSP premium years, covered members, ACA FPL cap, ACA regime override, and prior MAGI history for the IRMAA two-year 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, standard-versus-itemized deduction choice, state-taxable federally tax-exempt interest, LTCG/NIIT thresholds, explicit Roth basis layers, and same-year tax funding gross-up. Non-qualified HSA fallback distributions used for tax payments are included as ordinary income and carry the 20% additional tax before age 65; any qualified medical reimbursement capacity entered for an HSA is used first. Income streams and one-time rows are expanded into a sparse annual request, and missing income or deduction years default to zero 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 supports the contiguous 48 states and DC, Alaska, and Hawaii for the shipped FPL years.
• 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.