Expats spend their energy on the federal side: the foreign earned income exclusion, the foreign tax credit, the FBAR, the treaty. The state side gets a shrug. That shrug is expensive. State tax for expats and international clients runs on rules that have nothing to do with the Internal Revenue Code, and a state that still considers you a resident will tax your worldwide income with no exclusion, no foreign tax credit, and no treaty. I see this every week from our office in Park Ridge, outside Chicago: a family that moved to Dubai in 2022 and is still an Illinois resident on paper, a software engineer in Berlin whose California return was never closed, a J-1 researcher whose treaty exemption vanished the moment the state return was prepared. This post covers the state rules that actually bite: residency and domicile, the states that refuse to follow federal expat benefits, how nonresident aliens and dual-status filers are treated, and how to leave a state cleanly so the income you earn abroad stays abroad.
State Tax for Expats Starts with Domicile, Not Days
Federal residency for a citizen is simple: a U.S. citizen is always a U.S. tax resident. State residency is a two-part test, and most expats fail the part they never think about. Nearly every income tax state defines a resident as someone who is either domiciled in the state or who maintains a place of abode there and spends more than a threshold number of days (commonly 183) in the state. The day count is the easy half. An expat living in Singapore is not spending 183 days in Illinois. The hard half is domicile: the place you intend to return to, your permanent home, the place you have not abandoned even if you are not physically there.
Domicile does not change because you moved. It changes when you abandon the old one and establish a new one with the intent to remain. States prove domicile through the ordinary records of a life: where the house is, where the spouse and children are, where the driver's license, voter registration, car, bank accounts, doctors, and church are, where the furniture went, and what you told the moving company. A three-year expat assignment with the family home kept, the car in the garage, and the Illinois plates renewed every year is not a change of domicile. It is a temporary absence, and Illinois will say so.
Illinois defines a resident under 35 ILCS 5/1501(a)(20) as an individual present in Illinois for other than a temporary or transitory purpose, or an individual domiciled in Illinois who is absent for a temporary or transitory purpose. The Department's regulation at 86 Ill. Adm. Code 100.3020 adds two presumptions worth knowing: an individual who spends more than nine months of the year in Illinois is presumed a resident, and an individual absent from Illinois for a year or more is presumed a nonresident. That second presumption is helpful, but it is rebuttable, and it is rebutted by exactly the facts in the paragraph above.
The Sticky States: California, New York, Virginia, and the Rest
Some states let go. Some do not. If you left one of the following, assume the state still considers you a resident until you prove otherwise, because that is how their auditors approach it.
California taxes residents on worldwide income at rates up to 13.3 percent and treats domicile as a fact that persists until you affirmatively replace it. California does offer a safe harbor under Revenue and Taxation Code Section 17014(d): a domiciliary who is outside California under an employment-related contract for an uninterrupted period of at least 546 consecutive days is treated as a nonresident, provided return visits to California total 45 days or fewer per taxable year and the individual's intangible income (interest, dividends, capital gains from securities) does not exceed $200,000 in any year of the contract period. Miss any of those three conditions and the safe harbor is gone. The safe harbor also requires a contract; a self-employed expat or a remote employee with no formal foreign assignment does not qualify and is left to argue the closest-connections test the ordinary way.
New York has its own foreign presence rule for domiciliaries, the 548-day rule in Tax Law Section 605(b)(1)(A)(ii). A New York domiciliary is treated as a nonresident if, over any period of 548 consecutive days, he is present in a foreign country for at least 450 days, present in New York for no more than 90 days, and his spouse and minor children spend no more than 90 days in a New York permanent place of abode. The partial-year computation at the start and end of the 548-day window is proportional, and missing it by a handful of days converts the whole period back to resident status. New York also applies statutory residency separately: a permanent place of abode in the state plus more than 183 days of presence makes you a resident regardless of domicile, which is the trap for expats who keep the Manhattan apartment and come back for the summer.
Virginia does not have a safe harbor at all, and its Department of Taxation has historically taken the position that a Virginia domiciliary living abroad remains a Virginia resident until domicile is established elsewhere, including in the foreign country. New Mexico and South Carolina take similar positions. For expats leaving these states, the practical answer is usually to change domicile to a no-tax state before leaving the country, and to do it with real steps, not a mailing address.
The no-income-tax states are Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, and Wyoming. Two caveats: Washington imposes a separate tax on long-term capital gains above an indexed threshold, and every one of these states still requires that your domicile actually be there, which means something more than a mail-forwarding service. A Florida declaration of domicile filed with a county clerk, a Florida driver's license, a lease or ownership, and the relinquishment of the prior state's license and voter registration is the minimum package. States that lose a taxpayer to Florida know exactly what a paper move looks like and audit for it.
State Nonconformity: Where the FEIE, the Foreign Tax Credit, and Treaties Disappear
Once a state decides you are a resident, the second question is whether it follows the federal expat benefits. Most states begin the computation with federal adjusted gross income, and because the Section 911 exclusion reduces AGI before the state return starts, the FEIE flows through automatically in those states. Illinois is one of them: the Illinois starting point is federal AGI, so a properly claimed FEIE on Form 2555 reduces Illinois income too. Ohio, Michigan, Wisconsin, Colorado, and most others work the same way.
The exceptions are the states that build their own income base. California does not conform to Section 911. Foreign earned income excluded on the federal return is added back on Schedule CA, and California residents abroad pay California tax on the full amount. New Jersey and Pennsylvania compute gross income under their own statutes with no exclusion for foreign earned income. Massachusetts starts from federal gross income rather than AGI, and the Section 911 exclusion is not among the deductions Massachusetts permits, so foreign wages are fully taxable to a Massachusetts resident. If you are domiciled in one of these states while working abroad, the federal exclusion saves you federal tax and nothing else.
The foreign tax credit is worse. No state allows the federal Form 1116 credit against state tax, and only a handful allow any credit for foreign income taxes at all. Most states offer a credit for taxes paid to other states, and a few extend that credit to Canadian provinces, but taxes paid to Germany, the United Kingdom, or Japan generate no state relief anywhere I have practiced. A California resident earning wages in London pays U.K. tax, offsets federal tax with the foreign tax credit, and then pays California tax on the same wages with no offset. That is double taxation, and it is legal, because states are not parties to U.S. income tax treaties. If you need a fuller picture of how the federal credit works before layering the state on top, see our expat tax services page and the guide for U.S. citizens abroad.
Treaty positions follow the same logic. A treaty exemption claimed on Form 8833 binds the federal government and nobody else. Illinois, because it starts from federal AGI, effectively honors the exemption: the income never enters AGI, so it never enters Illinois income. States that start from federal gross income or from their own definitions do not. A J-1 researcher from Germany claiming the two-year teaching exemption under Article 20 of the U.S.-Germany treaty pays no federal tax on the salary, but if the university is in Massachusetts or California, the state return taxes it in full. I have prepared exactly that return this year. The client's federal liability was zero and the state bill was real, and the state bill was the surprise, because nobody had explained that treaty benefits stop at the state line.
Foreign Business Income at the State Level: NCTI, Subpart F, and Section 965
Individual shareholders of controlled foreign corporations have a separate state problem. Net CFC tested income (the regime that replaced GILTI under the 2025 legislation) and Subpart F inclusions are federal income items that land in AGI. States that conform to the current Code pick them up, but very few states allow the Section 250 deduction to individuals, because the federal deduction is available only through a Section 962 election or to a domestic corporation. The result is that an individual with a Form 5471 inclusion often pays state tax on the gross inclusion with no deduction and no credit for the foreign corporate taxes that reduced the federal bill. States also vary on whether they treat the inclusion as dividend income, business income, or something else, which affects apportionment and nonresident sourcing. Our GILTI and NCTI planning work now includes the state layer as a matter of course, and the Form 5471 engagement letter says so.
For inbound structures, the state layer runs the other direction. A foreign-owned U.S. LLC filing Form 5472 and a pro forma 1120 has no federal income tax liability if it is a disregarded entity with no effectively connected income, but the state where it is registered may impose a franchise tax, an annual report fee, or a gross receipts tax regardless. Delaware, Texas, Tennessee, and Washington all have obligations that a federal-only review misses. A Wyoming LLC with a Hong Kong parent is a clean structure federally and still owes Wyoming its annual license tax. The post-OBBB international changes did not touch any of this.
Nonresident Aliens, Dual-Status Filers, and the State Return Nobody Prepares
A nonresident alien filing Form 1040-NR has a federal return that taxes only U.S.-source and effectively connected income. The state does not care. A foreign national on an H-1B who arrives in July, becomes a dual-status filer for federal purposes, and moves into a Chicago apartment is an Illinois part-year resident from the move-in date. Illinois taxes the wages earned after that date. The state has no dual-status concept, no first-year choice election, and no interest in the substantial presence test; it applies its own domicile and presence rules to the same facts.
The problems cluster around three fact patterns. First, the year of arrival: the federal dual-status return splits the year at the residency starting date, while the state splits it at the date of domicile or the date presence began, and those dates are frequently different. Second, the treaty-exempt individual: F-1 students and J-1 scholars are exempt individuals for the federal substantial presence test, but a state does not recognize the exempt-individual category. A student who has lived in Champaign for three years and has never filed an Illinois return because "I am a nonresident for federal purposes" has three years of unfiled Illinois returns. Third, the departure year: a green card holder who leaves the United States in April and files a dual-status return for the year still owes a part-year state return through the departure date, and if domicile was never cleanly severed, a full-year state return.
Filing mechanics matter here. Illinois nonresidents and part-year residents file Form IL-1040 with Schedule NR to allocate income. New York uses Form IT-203 and its own allocation rules, which for wages count days worked in New York versus days worked everywhere. California uses Form 540NR. Each of these allocation schedules asks for information that the federal 1040-NR never requested, and each of them is the place where the state return either gets done correctly or generates a notice eighteen months later.
Leaving a State: The Exit Checklist and the Income That Follows You
No U.S. state currently imposes an exit tax on individuals who leave, although California has entertained proposals. What states do impose is continued taxation on income that is sourced to the state after you have gone, and continued residency on people who did not actually leave. The two are different problems with different fixes.
Changing domicile is a fact exercise, and the facts should be created before the departure date, not reconstructed afterward. The core steps: sell or lease out the home rather than leaving it vacant and available, move the spouse and children, surrender the driver's license and obtain one in the new jurisdiction, cancel voter registration, retitle and reregister vehicles, move bank and brokerage account addresses, change the address on the federal return, update estate planning documents to reference the new domicile, move safe deposit boxes and personal papers, and, for expats, obtain the foreign residence permit, lease, and local registration that show intent to remain abroad. The state auditor's question is always the same: if this person intended to leave, why does everything still point here?
Then there is the income that follows you regardless. Nonresidents are taxed by every state on income sourced to that state, and several categories are sourced to where they were earned rather than where you live when you receive them. Stock options and restricted stock units are allocated to the state where the services were performed during the vesting period, so an engineer who leaves California in 2026 with unvested RSUs will keep filing California nonresident returns for years as those units vest. Deferred compensation and bonuses earned in the state are sourced to the state. Gain on the sale of real property located in the state is taxable there by anyone. Income from a partnership or S corporation doing business in the state is sourced to the state through the entity's apportionment. Retirement income is the one category that federal law protects: 4 U.S.C. Section 114 prohibits any state from taxing the retirement income of a nonresident, so pension and IRA distributions are taxed only by your state of residence, and if that is a foreign country or a no-tax state, they are not taxed by any state at all.
Two housekeeping items close most files. File a final part-year resident return in the departure year, and mark it as such; a state that receives a full-year resident return the year you left has been told you did not leave. And keep filing nonresident returns for the trailing income above, because a state that has no return from you and sees a W-2 or K-1 with its name on it will assess as if you were a resident and let you prove otherwise.
What Illinois Expats Specifically Need to Know
Because most of our clients start here, a short list for Illinois domiciliaries going abroad. Illinois taxes residents at a flat 4.95 percent on federal AGI with Illinois modifications, so the FEIE and the treaty exemptions flow through cleanly. Illinois allows a credit for taxes paid to other states on Schedule CR but no credit for foreign taxes. Illinois grants an automatic six-month filing extension without a form, but the extension does not cover payment, and the late payment penalty and interest run from April 15. Illinois has no separate June 15 rule for taxpayers abroad; the automatic extension runs to October 15, but the tax was due April 15 regardless of where you lived. And the one-year absence presumption in 86 Ill. Adm. Code 100.3020 is your friend only if the rest of the file supports it: if the house is kept, the license is renewed, and the family visits every summer, expect Illinois to treat the absence as temporary.
For anyone leaving Illinois for a longer stay, my standing advice is to sever domicile deliberately in the year of departure, document it, file the part-year return, and stop. An Illinois resident abroad who keeps filing full-year resident returns "to be safe" is paying 4.95 percent of worldwide income for no reason, and the returns themselves are evidence that domicile never changed.
Where State Tax for Expats Fits in the Engagement
State analysis is part of every expat and international engagement at Qorri Tax, not an add-on. The intake questions cover the departure state, the domicile facts, the trailing income, and the destination, and the deliverable includes a state residency memo alongside the federal return. From Park Ridge we prepare returns in all fifty states, and the pricing is flat and set before the work begins. If you left a state and are not sure whether it agrees that you left, or you are arriving in one and do not know what it expects, that is precisely the conversation to have before the next return is filed rather than after the notice arrives. Start with a free consultation and bring the facts; the state will eventually ask for them anyway.