The apartment is the easy part. Illinois does not stop taxing you because you bought in Miami. It stops when your domicile changes, and for most families the tax that matters is not the one on income.
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This page explains how Illinois decides, why the estate tax is the number to plan around and where the Miami purchase actually fits. Your own position should be settled with a tax adviser before you sign anything. Contact the desk at Miami Dossier for the current position on any building we cover.
As of September 2026, Illinois taxes its residents on worldwide income at a flat 4.95 per cent, and Chicago adds no city income tax. That is a modest number by the standards of New York or California, and it is not the number most families are moving for. The Illinois question is decided by domicile, and what domicile carries with it is the estate tax.
Illinois calls you a resident if you are in the state for other than a temporary or transitory purpose, or if Illinois is your domicile and you are absent for a temporary or transitory purpose. Domicile is the one place you treat as your permanent home and intend to return to. You have exactly one at a time, and changing it takes intent plus action.
This is the trap. People count the income tax saving, decide it is not worth a fight, and leave the domicile question loose. The question does not go away. It waits for the estate.
Two presumptions frame the argument. Spend more than nine months of the year in Illinois and the regulations presume you are a resident. Be absent from Illinois for a full year and they presume you are not. Everything in between is decided on the facts, with the burden on you. Florida has no state income tax and no estate tax.
The Department of Revenue weighs where your permanent home is, where your business and professional life happens, how your time divides, where the things you care about are kept, and where your family lives. The Illinois driver licence, the voter registration and the change of address are worth doing and none of them decides anything.
Home. The two residences compared on size, value, use and upkeep. A Gold Coast apartment kept furnished and staffed, or a house in Winnetka that the family still gathers in, weighs against a lightly used Miami condominium.
Business. Where you physically make decisions. An office in the Loop you still walk into points at Illinois.
Time. Days here against days there, and the pattern. Summers in Lake Forest, three months in Miami and the rest travelling reads as an Illinois life.
Things and people. Where the art and the papers are, where a spouse lives, where the children are in school.
Selling the Illinois residence, or converting it to a genuine arm’s length rental, is the step that removes the strongest exhibit. Everything else is argument.
Illinois taxes estates above $4,000,000 at rates reaching 16 per cent. The exemption has not moved since 2013 and is not indexed for inflation, so a house on the North Shore, a business and a retirement account can cross it without anyone thinking of themselves as wealthy. The federal exemption is $15,000,000 per person. The gap between those two numbers is the exposure, and it is where most Illinois families who think their planning is done are in fact exposed.
Illinois does not recognise spousal portability. A couple that leaves everything to the survivor uses one exemption, not two, unless the documents were drawn to catch the first one. That is a planning question, not a domicile question, but a move is the moment people finally ask it.
The estate tax follows domicile. A resident of Florida with no Illinois property owes Illinois nothing. A resident of Florida who kept the Chicago apartment owes Illinois estate tax on the apartment, because Illinois taxes real property in the state whoever owns it. That is the second reason the kept apartment matters.
These figures should be confirmed against current law rather than taken from this page. A bill to raise the exemption was pending and not enacted as of mid 2026. The structural points, the flat exemption, the absence of portability and the reach to Illinois property, are the durable part.
One Illinois rule surprises people who have done everything else right. An irrevocable trust is an Illinois resident trust if the person who created it was domiciled in Illinois when it became irrevocable. The grantor moves to Florida. The trust does not.
Courts have limited the rule where a trust has no remaining connection to Illinois at all, no Illinois trustee, no Illinois assets, no Illinois beneficiaries, but that is a fact question argued case by case, not a default anyone should rely on. A family that settled trusts in Chicago in the 2000s and moves south in 2026 should expect those trusts to keep filing in Illinois until counsel says otherwise.
The point for the move is sequencing. Trusts that have not yet been made irrevocable are a different conversation after the domicile changes than before it. That conversation belongs with counsel and it belongs before the closing.
Buying here helps the home factor. A residence that is plainly the better home, actually lived in, with the near and dear things in it, is real evidence. A pied a terre held lightly while the Chicago apartment stays furnished and staffed is evidence in the other direction, and the Department reads it that way.
So the purchase is not the plan. It is one exhibit in the plan, and the order matters more than the address. Decide the domicile question with a tax adviser, decide what happens to the Illinois residence and to the trusts, and then choose the building. Reversing that order does not usually lose the argument, but it removes options that were free beforehand and expensive afterwards.
One practical item on the Florida side. Section 222.17 of the Florida Statutes lets you file a sworn Declaration of Domicile with the clerk of the circuit court in your county, which in Miami Dade is filed with the Clerk of the Courts. It is not required and it does not by itself decide anything. What it does is create a dated, sworn record of when you say the change happened, which is worth having in a process where you carry the burden.
Where the answer is neither: some people should not do this at all. If your business, your board seats and your children’s school are in Chicago, the honest advice is that the case is weak and the estate will be argued in Illinois. Buy in Miami because you want to be in Miami. That reason survives contact with an auditor.
This is the desk at Miami Dossier, a real estate desk. It is not a tax practice and does not pretend to be one. What it can do is make sure the property side of the decision is not the part that goes wrong.
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Residency and domicile are decided by tax law and by your own facts, and nothing on this page is tax advice. Contact the desk at Miami Dossier and we will go through the current position on any building we cover and where a purchase would sit against a move like this. Where a question is legal, tax or immigration, we introduce you to advisers who handle that properly rather than answering it ourselves.
