Federal tax is uniform across the United States; state tax is not. The same Roth conversion costs you 13.3% more in California than in Texas, and 0–10.9% more in New York depending on the bracket. Over a 10-year conversion window on a $3M pre-tax balance, the state-tax delta between a high-tax and no-tax domicile can run into the high six figures.
The California expatriation imperative Federal tax is a negotiation; California state tax on the wealthy is closer to confiscation, and the Franchise Tax Board (FTB) is the most aggressive state revenue agency in the country at pursuing departing residents. The 2026 stack as it applies to a retiree with significant income:
top at 12.3% on taxable income above roughly $700,000 single or $1.4M MFJ. A Roth conversion is ordinary income in California.
(formerly the Mental Health Services Tax, Prop 63) adds 1% on every dollar of taxable income above $1M, taking the combined CA top rate to 13.3%.
. Federal 0%, 15%, and 20% brackets do not exist in California; every realized gain is taxed at ordinary brackets.
under SB 951. The 2026 rate is roughly 1.1%–1.2% on every dollar of W-2 wages with no upper bound. This does not apply to a Roth conversion, an RMD, or a realized gain—it is a payroll tax on earned income—but it materially raises the cost of staying in California while drawing a W-2 consulting paycheck.
A $2,000,000 Roth conversion executed while domiciled in California costs an additional 13.3% on the top bracket, which on the dollars above the $1M BHST threshold is $133,000 of pure CA exposure on top of the federal 37% rate. The same conversion executed in Nevada, Texas, Florida, or Washington after a clean, properly documented domicile change costs zero. Across a ten-year ladder, this math is the price of a small estate.
The same is true to varying degrees of New York (top rate 10.9% and an aggressive auditor of departing residents) and Hawaii (top rate 11%). Oregon, Minnesota, and New Jersey land below those extremes but well above the no-tax states. If you have already accepted that you will pay federal tax on a large conversion ladder, leaving the state-tax exposure on the table is the financial equivalent of leaving the tip in your seven-figure dinner check.
The choreography of domicile Domicile changes are scrutinized aggressively. The state you are leaving will audit if the numbers are large. Establish domicile in your no-income-tax state before the year of large conversions or realizations. Domicile is a factual determination: voter registration, driver’s license, primary residence, time spent, the location of your physicians and financial advisors, and even your planned burial plot. California’s FTB is notoriously litigious; New York is the most aggressive in the country.
Time large conversions and realizations into post-move years. A single conversion in the wrong domicile year can pay for the entire cost of the move. Be exceptionally careful with part-year resident filings; a move during a tax year often produces a prorated state liability. A conversion executed before the move date attaches to the prior state. If you plan to retire to a high-tax state for family reasons, front-load conversions in the low-tax origin state in the years immediately before the move.
Day-count evidence A residency audit lives or dies on whether you can show, day by day, where you slept. Both the CA FTB and New York run on the statutory-day test. Reconstructing that calendar two years after the fact from credit-card swipes and calendar entries is a losing exercise. The auditor has subpoena power over your phone logs, E-ZPass accounts, and bank statements, and they will use it. Mobile residency trackers—such as Monaeo, TaxBird, or TaxDay—run silently in the background, count days against each jurisdiction’s threshold, alert you before you trip one, and export an audit log your CPA can hand over on demand. The annual subscription is a rounding error against the tax exposure they document.
The move itself is rarely the goal. But once a move is on the table, the conversion calendar should be built around it. Treat the year of domicile change as the most valuable single-year arbitrage available in retirement planning, and do not waste it.