Short answer
A residency change has to clear two independent tests. You must break domicile in the old state, which turns on intent proved by facts, and you must not trip the old state's mechanical residency test, which in New York is maintaining a permanent place of abode plus more than 183 days in the state. California has no day-count test and instead presumes residence if you spend more than nine months there, with the important asymmetry that spending less than nine months creates no presumption that you are a nonresident. But for most practice sellers the decisive issue is not residency at all. It is sourcing. New York Tax Law 632(a)(2) makes the deemed asset sale from a 338(h)(10) election New York source income to a nonresident shareholder, and California courts have held that a pass-through entity's gain on selling goodwill is California source income to nonresident owners. Moving protects a clean stock sale far better than it protects an asset or goodwill sale. There is no statutory waiting period, and any specific number of months you have been quoted is practitioner habit rather than law.
Key facts
- Two separate tests
- Domicile (intent plus facts) and statutory residency (mechanical). Failing either makes you a resident.
- New York day count
- Permanent place of abode plus more than 183 days in New York makes you a resident regardless of domicile. Part days count.
- California has no 183-day test
- It uses temporary or transitory purpose. More than nine months creates a presumption of residence; less than nine months creates no presumption of nonresidence.
- The rule that usually decides it
- Sourcing. An asset sale or goodwill sale by a business operating in the old state is often taxed there no matter where you live.
- 338(h)(10) and New York
- Tax Law 632(a)(2) treats the deemed asset sale as New York source income to the nonresident shareholder, by statute.
- Waiting period
- There is none in statute or regulation. Any specific number of months is rule of thumb, not law.
Two tests, not one
A residency change fails if you miss either of two independent tests, and they work on completely different logic. The first is domicile, which is about intent proved through facts. Your domicile is your true, fixed, permanent home, the place you mean to return to whenever you are away. You have exactly one at a time, and under California's regulation you keep the one you have until you actually acquire another somewhere else. Simply leaving does not do it. You have to land.
The second is statutory residency, and it does not care about your intent at all. New York treats you as a resident if you maintain a permanent place of abode in the state and spend more than 183 days there during the year. A physician with immaculate Florida domicile facts who keeps a Manhattan apartment and works enough New York days is a New York resident on worldwide income, and worldwide income includes the gain on the practice.
Two details catch people. Part days count as days in New York, so flying in for a morning meeting is a day. And a 2022 New York appellate decision narrowed what counts as a permanent place of abode, holding that a taxpayer must have a residential interest in the property and actually use it as a residence, rather than merely maintaining a dwelling that could serve as one. That is genuine help for a true vacation house used a few weeks a year. It is no help at all for the apartment you keep because you still work there.
California works differently, and less generously than people assume
California has no 183-day rule. It asks whether you are in the state for other than a temporary or transitory purpose, and it treats anyone domiciled in California who is outside the state for a temporary or transitory purpose as a resident. There is a day-count presumption, but it runs one way only. Spending more than nine months in California in a tax year presumes you are a resident. Spending less than nine months creates no presumption that you are not, and the regulation says so directly. A person can be a California resident while spending very little time in the state.
That asymmetry is the single most misunderstood thing about leaving California. Counting days down is not a strategy there. What California weighs is the strength of your connections, and its published guidance is explicit that the strength of the ties matters rather than the number of them.
The factor list California uses comes from a 2003 State Board of Equalization decision and covers the expected ground: where your homes are and their relative size and value, where your spouse and children live, where the children attend school, where you claim a homeowner's property tax exemption, days spent in each state and why, where you file returns and what residence you claim on them, bank account locations, where checking and credit card transactions originate, club and religious and professional memberships, vehicle registration, driver's license, and voter registration.
Three items on that list are worth a physician's particular attention. Where your professional licenses are held is an enumerated factor, and a doctor who moves to Nevada while maintaining an active California medical license and California hospital privileges has handed the auditor a fact. So is where you obtain professional services, which expressly includes your own doctors and dentists. And so is where your business interests are owned, which is awkward when the thing you are selling is a California practice.
The rule that decides more money than residency does
For most practice sellers, the question that matters is not where you live when the deal closes. It is whether the gain is sourced to the old state regardless. This is the part that gets left out of the move-to-Florida pitch, and it is usually worth more than everything else on this page combined.
The general rule is favorable. A nonresident's income from intangible personal property, meaning stock and similar assets, is generally not taxable by the old state unless the property has acquired a business situs there. If you genuinely move and then sell the stock of a corporation, that is the regime you want to be in.
The exceptions swallow a great deal of it, because most of these deals are not clean stock sales. New York Tax Law 632(a)(2) states that where the shareholders of an S corporation make a 338(h)(10) election, the gain recognized on the deemed asset sale is treated as New York source income, allocated under the corporate rules, in the year of the election. That is a statute, not an argument. A New York practice sold as an asset sale or with that election produces New York source income to a seller living in Florida. The same provision reaches installment obligations distributed under the related federal rule, allocating the gain consistently with the year the assets were sold.
California reaches a similar destination by a different route. A California appellate court held that nonresident shareholders of an S corporation owed California tax on their share of the gain when the corporation sold its goodwill, reasoning that the gain was apportionable business income under the uniform allocation rules so the corporate-level rules controlled, and alternatively that the goodwill had acquired a California business situs. Selling through a holding company conduit has also drawn challenge.
The practical translation is short. Moving protects a clean sale of stock reasonably well. It protects an asset sale or a goodwill sale by a practice that operated in the old state considerably less, and often not at all on the entity-level gain. Since the structures these buyers use are usually asset sales or F-reorganizations rather than clean stock sales, this is the ordinary case rather than the exotic one. The structure page explains which is which.
Installment payments after you leave
California's treatment here is source-based rather than residence-based, which helps in one direction and hurts in the other. California taxes installment gains received by a nonresident when the underlying property was sourced to California. But its guidance also states that a former California resident's installment proceeds from the sale of property located outside California, sold while they were a resident, are not taxable by California. And the mirror image applies: someone who sells non-California property on installment and then becomes a California resident is taxed on the payments received while resident, which is a trap for a physician moving into California after a sale elsewhere.
If your deal includes an earnout or a note, this interacts with the federal installment rules in ways that are worth modeling rather than assuming. The earnouts and 453A page covers the federal side.
What the file has to look like
New York's audit guidelines group the domicile inquiry into five primary factors, and they are a good checklist regardless of which state you are leaving. The home, comparing the residences by size, value and how each is actually used. Active business involvement. Time, meaning days. Items near and dear, which means heirlooms, art and the possessions people keep where they actually live. And family connections, including where a spouse and minor children live and where the children go to school.
The documents auditors ask for are ordinary and specific: calendars and appointment logs, credit card receipts, phone and cell records, bank statements and where correspondence is addressed, insurance policies that show where valuables sit, vehicle registration, driver's license, voter registration, school enrollment records, moving bills and bills of lading, and affidavits from people who know your situation.
The pattern that loses is easy to describe. Renting a modest condo in the new state while keeping a larger owned home in the old one, with the spouse and children still there, the medical license still active there, the same physicians and dentists, the same clubs, and a day count that is close. Each item alone is survivable. Together they describe someone who has not actually moved.
How long before the sale
There is no waiting period in any statute or regulation in either California or New York. The six months, twelve months, or two tax years you may have been told about are practitioner rules of thumb, and it is worth knowing that they carry no legal weight, because it changes what you should be optimizing.
What the law supplies instead is three things. California's nine-month presumption runs against you and not for you, so a short absence proves nothing affirmatively. New York's tests are calendar-year tests, which means the year of the closing is the year that has to be clean rather than some trailing period. And sourcing does not improve with time at all, so if the gain is New York source or California source, moving early changes nothing about it.
Moving before the letter of intent is signed is sensible practice, because a move that happens after a deal is effectively agreed looks like what it is, and because the facts you build take time to become real. That is prudence rather than a cited rule, and it is worth stating honestly as prudence.
Declarations of domicile and the safe harbor
Florida and Nevada both let you record a sworn declaration of domicile, under Florida Statute 222.17 and Nevada's NRS 41.191 respectively, filed with the county court clerk. File one. It is useful evidence of intent and it costs almost nothing. It is not conclusive, and the Florida statute says so expressly in a closing sentence preserving all other methods of proving domicile. Anyone presenting a recorded declaration as the thing that settles the question is overselling a form.
California's safe harbor deserves a mention only so you can stop considering it. It treats a California domiciliary as a nonresident during an absence of at least 546 consecutive days under an employment-related contract, with return visits capped at 45 days a year. It does not apply if you have more than $200,000 of income from intangible personal property in any taxable year, and it does not apply where the principal purpose of the absence is avoiding tax. A practice sale defeats the first condition by itself, and the second was written for precisely this fact pattern.
What to do next
Work the questions in the order that reflects where the money is. First, find out how your deal is structured, because a clean stock sale and an asset sale lead to different answers and the structure is usually the buyer's preference rather than yours. Second, determine whether your gain is sourced to the state you are leaving, since that is frequently decisive and is unaffected by timing. Only third does the residency work itself matter, and if it does, start it well before a letter of intent and build a real file rather than a paper one.
The state pages carry the specifics for California and New York on the departure side, and for Texas, Florida and Nevada on the arrival side. The calculator will show you what the state rate is actually worth against the federal bill, which is often a smaller share of the total than expected. This page is educational and is not legal advice; a residency change of this size should be built with your transaction attorney, and it is something we work through with clients as part of a term-sheet review.
Questions people ask
How long before the sale do I need to move?
There is no statutory or regulatory answer, in California or New York, and anyone quoting you a specific number of months is repeating practitioner habit rather than citing law. What the statutes actually supply are different constraints. California presumes residence if you spend more than nine months in the state in a tax year, and explicitly does not give you the reverse presumption for spending less. New York's tests run on the calendar year, which as a practical matter means the year the deal closes is the year that has to be clean. And the doctrine that matters most, sourcing, does not improve with time at all: if the gain is sourced to the old state, moving three years early does not change that.
What is the difference between domicile and statutory residency?
Domicile is your true, fixed, permanent home, the place you intend to return to whenever you are away. You have exactly one, and you keep it until you actually acquire another. Statutory residency is mechanical and ignores intent entirely: New York treats you as a resident if you maintain a permanent place of abode in the state and spend more than 183 days there, even if you are unquestionably domiciled in Florida. They are separate hooks, and you have to clear both.
I moved to Florida but kept my New York apartment. Am I safe?
Possibly not. If you keep a permanent place of abode in New York and spend more than 183 days there, you are a New York resident on your worldwide income for that year, including the gain on your practice sale, no matter how good your Florida facts are. Part days count as days in New York, which surprises people who fly in for a morning. A 2022 New York appellate decision did narrow what counts as a permanent place of abode, holding that the taxpayer needs a residential interest in the property and must actually use it as a residence, so a dwelling that merely could serve as one is not automatically enough. That helps a genuine vacation property. It does not help a working apartment.
Does moving protect the gain on my practice sale?
It depends entirely on what is being sold, and this is where most of the money is won or lost. A nonresident's gain on selling an intangible, such as stock, is generally not taxable by the old state unless the property has acquired a business situs there. But an asset sale, or a sale of goodwill by an entity operating in the old state, is treated very differently. New York Tax Law 632(a)(2) provides by statute that if the shareholders make a 338(h)(10) election, the gain on the deemed asset sale is New York source income allocated under the corporate rules. California courts have held that a nonresident shareholder of an S corporation owed California tax on a share of the gain from the corporation's sale of goodwill, on the reasoning that it was apportionable business income, and alternatively that the goodwill had a California business situs. So moving helps a clean stock sale far more than it helps an asset or goodwill sale, which is the structure most of these deals use.
What about installment payments I receive after I move?
California's rule is source-based rather than residence-based, which cuts both ways. California taxes installment gains received by a nonresident where the underlying property was sourced to California. But its published guidance also states that a former California resident's installment proceeds from the sale of property located outside California, sold while they were a resident, are not taxable by California. The mirror image is also true: a nonresident who sells non-California property on installment and later becomes a California resident is taxed on the payments received while a resident. New York's 632(a)(2) similarly reaches installment obligations, allocating gain consistently with the year the assets were sold.
What do auditors actually look at?
New York's audit guidelines organize the domicile question around five primary factors: the home, comparing size, value and how each is used; active business involvement; time, meaning days; items near and dear, such as heirlooms and art; and family connections, including where a spouse and minor children live and where the children attend school. Auditors ask for calendars and appointment logs, credit card receipts, phone bills and cell records, bank statements, insurance policies that locate valuables, vehicle registration, driver's license, voter registration, school enrollment, and moving bills. California's factor list from a 2003 State Board of Equalization decision covers similar ground and adds several that matter for a physician specifically, including the state where professional licenses are held and where you obtain professional services such as doctors and dentists.
Does a Declaration of Domicile settle it?
No. Florida Statute 222.17 and Nevada's NRS 41.191 both let you file a sworn declaration of domicile with the county court clerk, and both are worth filing. Neither is conclusive. The Florida statute closes with an express savings clause preserving all other methods of proving and evidencing domicile, which is the legislature saying plainly that this document is evidence rather than proof. Treat it as one useful item in a file that should contain many.
Does California's safe harbor help me?
Almost certainly not, and it is worth knowing why so you do not waste time on it. The safe harbor treats a California domiciliary as a nonresident during an absence of at least 546 consecutive days under an employment-related contract, with visits back totaling no more than 45 days a year. But it does not apply if you have income from stocks, bonds, notes or other intangible personal property exceeding $200,000 in any taxable year, and it does not apply if the principal purpose of the absence is avoiding tax. A practice sale blows through the intangible income cap on its own, and the anti-avoidance clause is aimed squarely at this situation.