Key Biscayne property taxes are levied by Miami-Dade County on an assessed value set by the County Property Appraiser, with combined millage from the county, the Village of Key Biscayne, the school district, and other authorities. Florida has no state income tax, homesteaded primary residences receive an exemption and a Save Our Homes assessment cap, and new construction is assessed at current value rather than inheriting a prior owner's capped basis.
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Florida's tax profile is the reason a large share of Key Biscayne buyers are relocating rather than trading up locally: no state income tax, and a property tax system with meaningful protections for primary residents. The trade-off is that property taxes and insurance are the recurring costs that matter, and on a new-construction oceanfront purchase they are assessed on today's value rather than a decades-old basis. This guide explains the mechanics so you can model a real annual figure before you contract.
Who Levies What
A Key Biscayne condominium tax bill combines several taxing authorities: Miami-Dade County, the Village of Key Biscayne, the Miami-Dade County school district, and additional special districts and authorities. Each sets its own millage annually, so the combined rate changes year to year and should be confirmed against the current-year rates published by the county rather than assumed from an older bill.
The Miami-Dade Property Appraiser publishes assessed values and exemption information per folio, which makes verification straightforward for any specific existing residence.
Homestead, Save Our Homes, and Portability
Florida's homestead exemption reduces the taxable value of a primary residence, and the Save Our Homes provision limits how much assessed value can increase annually for homesteaded property. Over long ownership periods that cap produces very large gaps between market value and assessed value — which is exactly why a seller's historical tax bill is a misleading guide to what a buyer will pay.
Portability allows eligible homesteaded owners moving within Florida to carry accumulated Save Our Homes benefit to a new homestead, subject to statutory caps and filing deadlines. Buyers relocating from another Florida property should raise portability with their tax advisor early, since the filing window matters.
Second Homes and Investment Ownership
Non-homesteaded property — second homes, pieds-à-terre, and investment condominiums — does not receive the homestead exemption and is subject to a different, higher annual assessment cap. Many Key Biscayne oceanfront residences are held this way, which means comparable units in the same building can carry very different tax bills depending on the owner's status.
Investors modelling net yield should use the non-homesteaded figure. Our Key Biscayne condo rental income guide combines taxes and assessments into a net return framework.
Taxes on New Construction
New construction is assessed on the completed improvement and sale value, so a purchase at 301 Ocean Drive should be modelled from the purchase price rather than from any neighbouring building's tax history. In the first year or two after delivery, assessments can also be adjusted as the appraiser completes valuation of a newly delivered building.
Practically, the right approach is to apply current combined millage to your expected purchase price for a conservative estimate, then add condominium assessments to reach a monthly carrying figure.
International Buyers and Tax Planning
Foreign buyers face additional considerations beyond annual property tax: FIRPTA withholding on eventual sale, entity structuring decisions, and estate tax exposure on US-situs assets. These are planning items to resolve before contract, because retroactive restructuring is expensive.
Our foreign buyer guide covers FIRPTA, financing, and structuring. Nothing on this page is tax or legal advice — confirm your position with a Florida real estate attorney and a cross-border tax advisor.
How the tax calculation works
| Step | What happens | Buyer note |
|---|---|---|
| Assessed value | Set annually by the Miami-Dade Property Appraiser | Resets on sale and new construction |
| Exemptions | Homestead and other exemptions applied | Primary residences only for homestead |
| Assessment caps | Save Our Homes for homestead; separate cap otherwise | Second homes cap higher |
| Millage | County, Village, school district, other authorities | Set each year; confirm current rates |
| Tax bill | Millage applied to taxable value | Payable annually, discounts for early payment |
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Register for Priority AccessFrequently Asked Questions
How are Key Biscayne property taxes calculated?
The Miami-Dade County Property Appraiser sets an assessed value, exemptions are applied, and the combined millage rates of the county, the Village of Key Biscayne, the school district, and other taxing authorities are levied on the taxable value. Rates are set annually, so current-year millage should be confirmed with the county.
Does Florida have a state income tax?
No. Florida levies no state personal income tax, which is a primary reason high-net-worth buyers relocate to Miami-Dade. Property taxes and insurance are the meaningful recurring costs of ownership instead.
What is the homestead exemption and Save Our Homes cap?
Florida's homestead exemption reduces taxable value on a primary residence, and the Save Our Homes provision caps annual increases in assessed value for homesteaded property. Non-homesteaded property, including second homes and investment condos, is subject to a different, higher cap.
Will taxes be higher on new construction like 301 Ocean Drive?
Generally yes relative to a long-held homesteaded residence, because the assessment resets at the new value on completion and sale rather than carrying forward a capped basis. Buyers should model taxes on purchase price rather than on a seller's historical tax bill.
Can I transfer my existing Florida tax cap to a new purchase?
Florida portability allows eligible homesteaded owners to transfer accumulated Save Our Homes benefit to a new Florida homestead, within statutory limits and deadlines. Eligibility and amounts should be confirmed with the Property Appraiser or your tax advisor.