A Roth conversion does not have one national state-tax result. Start with the federal taxable amount, then determine the owner's resident, part-year resident, and nonresident status on the transaction date; each state's IRA basis and retirement-income adjustments; local tax; payment requirements; and any benefit program that uses its own income definition. A move can change the result, but a new mailing address alone does not establish a tax residence or prove savings.
This guide organizes a state-tax investigation. It does not calculate a state return, determine domicile, list every state rule, approve a move, allocate multistate income, or recommend a Roth conversion. State law, forms, administrative guidance, local taxes, and household facts can change during 2026.
What state-tax question follows the federal conversion?
First calculate the federal transaction correctly. A traditional IRA conversion generally includes the pretax portion in federal income, while documented after-tax basis is not taxed again. Form 8606 generally allocates one owner's IRA basis across traditional, SEP, and SIMPLE IRAs under the federal rules. An employer-plan rollover can use different source records.
The state return then asks separate questions. A state may begin with a federal income measure but require additions or subtractions. It may have its own record of contributions already taxed by that state, a retirement-income subtraction, age or income conditions, part-year allocation, or no broad individual income tax. The gross amount transferred, federal taxable amount, state taxable amount, and cash tax are therefore four different fields.
Do not use a custodian's Form 1099-R as the final state answer. Preserve the Roth conversion overview records first, then reconcile each state return from the same transaction.
Why is a no-tax or high-tax state list not enough?
A headline list can identify questions, but it cannot calculate a household's result. Even a state without a broad tax on ordinary individual income can have local taxes, special taxes, property-tax or benefit rules, filing obligations, and a different cost of living. A state with an income tax may exclude some retirement distributions or preserve basis that the federal return does not.
| Question | Evidence to collect | What the answer controls |
|---|---|---|
| Who taxes the owner as a resident? | Domicile, statutory-residency, part-year, and nonresident rules | Which state can reach worldwide income and for what period |
| What amount enters the state return? | Federal return, state additions, subtractions, and IRA basis | State taxable conversion amount |
| Does a retirement rule apply? | Account type, age, income, plan, distribution, and state instructions | Exclusion, subtraction, phaseout, or no adjustment |
| Is there another jurisdiction? | Local return, work location, source income, and credits for other-state tax | Additional tax, allocation, or credit |
| Does another program count the amount? | Program statute, application, worksheet, and tax-return definition | Property-tax relief, healthcare, or assistance eligibility |
Use the official tax agency for every state involved. USA.gov maintains a directory to state tax agencies, but the linked state's current instructions and forms remain the operative source.
How can states treat the same conversion differently?
Official state guidance shows why a generic percentage is unreliable. These examples are evidence patterns, not a complete state comparison or a promise that the same treatment applies to every account and taxpayer.
| Official example | Rule to verify | Planning lesson |
|---|---|---|
| Illinois | The Illinois Department of Revenue lists the federally taxed portion of a traditional IRA converted to a Roth IRA among qualifying retirement-income subtraction items. | A state subtraction can make the state amount differ from federal income; confirm the return line and eligibility. |
| New Jersey | New Jersey says amounts converted from a traditional IRA that were not previously taxed by New Jersey are included in state income, while previously taxed contributions generally are not taxed again. | New Jersey and federal basis records can differ; preserve state contribution and rollover history. |
| California | California taxes a part-year resident on worldwide income received while resident and California-source income received while nonresident. | The transaction date and supported residency period matter; the annual address is not an allocation method. |
| New Jersey benefit programs | New Jersey's Senior Freeze income guidance includes Roth IRA distributions or rollovers in program income and can count a Roth rollover even when it is not taxable for New Jersey income-tax purposes. | Zero state income tax on an item does not prove zero household cost under another program's definition. |
These differences also show why retirement-income labels are too broad. Pension payments, traditional IRA distributions, qualified plan rollovers, Roth conversions, Roth distributions, and Social Security can occupy different lines and follow different state definitions.
Can a former state tax a conversion after a move?
Federal law in 4 U.S.C. Section 114 generally limits a state from imposing income tax on certain retirement income of a person who is not a resident or domiciliary of that state. The statute's retirement-income definition includes specified qualified plans and individual retirement arrangements. This is an important boundary, but it does not decide the threshold question: whether the person actually became a nonresident under the former state's law.
A state can examine domicile, statutory residency, the date residence changed, part-year reporting, source income, and other connections. The federal protection also does not calculate the new state's tax, state-specific basis, local tax, credits, estimated payments, or benefits. A person with homes or substantial ties in two states needs a documented conclusion for both states rather than the slogan, "I moved before converting."
California, for example, directs part-year residents to report worldwide income while resident and California-source income while nonresident. New York separately publishes resident and nonresident guidance and warns that domicile and statutory residency are distinct tests. Use the actual former and new state rules, not one state's checklist as a national standard.
What evidence supports the move date?
Domicile generally turns on facts and intent demonstrated by actions. No single document should be treated as a universal safe harbor. State tests differ, and a driver's license or voter registration can be relevant without controlling the entire result.
| Evidence group | Records | Question to resolve |
|---|---|---|
| Homes | Closing statements, leases, utilities, insurance, exemptions, and occupancy | Which home was established, retained, available, or abandoned and when? |
| Time | Calendars, travel, tolls, card records, medical visits, and workdays | Where was the person physically present under each state's day test? |
| Family and possessions | Spouse, dependents, pets, vehicles, valuables, and household moves | Where did ordinary home life continue? |
| Economic ties | Employment, business, property, professional relationships, and banking | Which ties continued and whether they create source income? |
| Formal acts | License, vehicle, voter, tax, estate, mailing, and account records | Do dated actions consistently support the claimed residence? |
Build the timeline before choosing the conversion date. Inconsistent facts should be resolved with a professional familiar with both states. Do not create records after an audit begins and describe them as contemporaneous evidence.
How should convert-now and convert-after-moving scenarios be compared?
Use identical account values, investment assumptions, spending, conversion amount, federal income, tax-payment source, and time horizon. Change only the facts that genuinely differ by date and location. A comparison that gives the after-move case a lower state tax while also assuming better markets, lower spending, and no moving costs does not isolate the move.
- Prepare a no-conversion case for the current state and year.
- Calculate lower, middle, and upper current-year conversion candidates.
- Repeat the same amounts for the proposed post-move resident period.
- Apply each state's basis, additions, subtractions, exclusions, local tax, and payment rules.
- Add moving, housing, insurance, healthcare, travel, and professional costs that change between cases.
- Recalculate federal tax, Social Security taxation, Marketplace credits, later IRMAA, RMDs, and liquidity.
- Include a delayed-move case and a case in which the residency position is challenged.
- Approve only the current-year transaction after the move facts and current instructions are documented.
The conversion timing guide owns the current-year amount range. The multi-year guide keeps later years as scenarios rather than approved transactions.
What filing and payment issues belong in the worksheet?
A favorable state tax treatment does not remove administration. Determine whether the custodian will withhold state tax, whether withholding is permitted or required, which state receives it, whether an estimated payment is due, and how a part-year return reports the transaction. An unnecessary withholding can reduce what reaches the Roth and may require a refund claim; missing a required payment can create interest or penalties.
Keep the transaction date, confirmation, withholding election, payment date, voucher, extension, federal return, each state return, and final assessment together. Reconcile the state taxable amount to the federal form and the state's basis worksheet. If a notice arrives, answer from those records rather than reconstructing the move and conversion years later.
Can a conversion affect state benefits without state income tax?
Yes. A credit or assistance program can use gross income, federal AGI, state taxable income, household income, resources, or a purpose-built definition. New Jersey's Senior Freeze guidance is a concrete example: its program income can include Roth IRA rollovers even when the same rollover is not taxable for New Jersey income-tax purposes.
Before converting, identify every state or local property-tax program, healthcare program, prescription assistance benefit, housing benefit, or other income-tested resource used by the household. Read the program's current worksheet and measurement year. Do not assume the income-tax return line controls another program or that a conversion affects only the year cash moves.
A 2026 state-tax conversion checklist
- Identify the owner, source account, destination, gross amount, federal taxable estimate, and transaction date.
- Retrieve federal Form 8606 and every relevant state's basis and retirement-income records.
- List each possible resident, part-year resident, nonresident, and local return.
- Build a dated domicile and physical-presence evidence file before relying on a move.
- Use each state tax agency's current instructions, forms, additions, subtractions, and payment rules.
- Apply 4 U.S.C. Section 114 only after confirming nonresident status and covered retirement income.
- Model no conversion, several current-state amounts, and matched post-move amounts.
- Recalculate tax, credits, benefits, healthcare, moving costs, liquidity, and later-year plan effects.
- Obtain written plan or custodian instructions and confirm withholding before execution.
- Reconcile Forms 1099-R, 5498, 8606, state returns, payments, and residency records after filing.
RetireStride provides educational retirement-planning information, not individualized tax, legal, residency, investment, benefits, or relocation advice. State and local law, administrative positions, forms, basis, domicile, physical presence, account type, household programs, and transaction facts can change the result. Confirm material positions with current official instructions and qualified professionals in every affected jurisdiction.