The question of which state gets to tax retirement income earned in one state but paid out after moving to another used to be a real, unresolved problem, and California was at the center of it. Before 1996, several states, California prominent among them, attempted to tax pension and retirement account distributions paid to former residents on the theory that the income had been earned, and the tax deferral created, while the person was still a California resident and employee.

Congress resolved this with the Pension Source Tax Act, codified at 4 U.S.C. § 114, which flatly prohibits any state from taxing retirement income paid to someone who is not currently a resident or domiciliary of that state. The law defines 'retirement income' broadly to include qualified employer plans (401(a), 401(k)), simplified employee pensions, 403(a) and 403(b) annuity plans, individual retirement accounts, eligible deferred compensation plans, and most governmental pension plans. Once you're genuinely no longer a California resident or domiciliary, California has no legal ability to tax distributions from any of these account types, no matter how many years of California-based earnings and contributions built up the balance.

This means the source of the money, where it was earned, where the employer was located, where contributions were originally made, is legally irrelevant once you've established residency elsewhere. Only your current state of residence taxes the distribution. For a genuine Arizona resident with a pension or 401(k) built up entirely during a California career, Arizona's flat 2.5% is the entire state tax bill on that income; California cannot layer its own tax on top.

The word 'genuine' is doing real work in that sentence, and it's where most of the practical risk actually sits. This federal protection only applies once residency and domicile have actually, provably shifted, it doesn't apply the moment you decide you'd like it to, or the day you close on an Arizona home while still spending most of your time and maintaining most of your life in California. California is known for scrutinizing claimed departures, particularly for higher-income taxpayers, and the burden of proving the change of domicile sits with the taxpayer, not the state.

This law specifically doesn't cover every form of deferred compensation. Certain non-qualified deferred compensation arrangements, stock options, and some executive compensation plans fall outside the statute's protection and may still be subject to allocation or apportionment between states based on where the compensation was actually earned. This is a narrower, separate issue from ordinary qualified retirement plan and IRA distributions, and worth flagging specifically for anyone with equity compensation or a non-qualified deferred comp plan from a California employer.

In practice, this federal protection is one of the more favorable, underappreciated facts for anyone relocating from California to Arizona in retirement. It means the entire, sometimes decades-long accumulation in a 401(k), pension, or IRA doesn't carry a lingering California tax obligation once the move is genuinely completed, the tax picture resets entirely to Arizona's rules going forward.

This is also why the timing and documentation of the move matter more than the mechanics of the retirement accounts themselves. The accounts don't need to be moved, converted, or restructured to get this protection, an IRA or 401(k) built entirely in California carries no special tag or flag that follows it to Arizona. The protection is a function of where you live and are domiciled at the time of each distribution, not a function of the account's history or where it happens to be custodied.

This is worth knowing early rather than discovering it after a distribution has already been taken and taxed incorrectly, or after California has already raised a residency question. Getting the domicile timeline right before a large distribution or Roth conversion is a much easier position to be in than trying to unwind the tax treatment after the fact.

If you're planning to move from California to Arizona, understand that the federal law protecting your retirement account distributions from continued California taxation only takes effect once your change of domicile is genuine and complete, not the moment you decide to move or even the day you close on an Arizona home. Establish Arizona domicile fully, driver's license, voter registration, primary home, before relying on this protection for a large distribution or Roth conversion.

If you have non-qualified deferred compensation, stock options, or other executive compensation from a California employer in addition to a standard 401(k) or pension, get specific advice on how those particular arrangements are treated, they generally aren't covered by the same federal protection and may still be subject to California tax based on where the compensation was originally earned.

• Assuming California can still tax a pension or 401(k) simply because the money was earned there, federal law specifically prohibits this once you're a genuine resident of another state.
• Assuming the federal protection kicks in immediately upon deciding to move, rather than once domicile has actually, provably shifted.
• Applying this protection to non-qualified deferred compensation, stock options, or other executive compensation, which generally fall outside the statute and may still be taxable by California based on where they were earned.
• Not documenting the change of domicile thoroughly enough to defend the position if California questions it, particularly for higher-income departures.