A home of $4M or more on Miami Beach's barrier islands is financed in 2026 with a jumbo mortgage, because Miami-Dade County's conforming loan limit is $832,750 — the national baseline, and a fraction of what any purchase here requires. The market runs from full-floor condominiums in South Beach, Mid-Beach and the new Bal Harbour towers to guarded bayfront estates on Star, Palm and Hibiscus Islands, with Surfside in between, and a large share of its buyers could pay cash. Those who borrow instead usually do so to keep capital at work. One structure built for that position is The Family Office Mortgage, a privately offered program that pairs a jumbo mortgage with a premium-financed indexed universal life insurance policy — a structured financial product whose projected payout is sized to the loan's later payments.
Why nearly every purchase here is a jumbo loan
Each year the Federal Housing Finance Agency sets the largest mortgage Fannie Mae and Freddie Mac may buy. For 2026 the baseline for a one-unit home is $832,750, and high-cost areas reach a ceiling of $1,249,125. Miami-Dade County sits at the baseline; Florida's only county above it is Monroe, the Keys, at $990,150. The state's most expensive coastal market is, by federal measure, not a high-cost area.
The arithmetic is not close. With 20% down on a representative $5,000,000 home, the loan is $4,000,000 — nearly five times the county limit. A jumbo cannot be sold to the agencies, so each lender keeps the loan or places it privately and writes its own down-payment, reserve and pricing terms. How an interest-only jumbo mortgage works covers the structure, including the rule that matters most for planning: the lender qualifies you against the later, fully amortizing payment, not the interest-only one.
How buyers here actually finance
This is a second-home market with an international buyer base — the Northeast and the Midwest, Latin America and Europe — and cash is the default competitor. Cash removes the financing contingency, and in a negotiation over an island estate that certainty counts. What it costs is liquidity in one coastal asset, and, if the cash came from selling appreciated holdings, a capital gains tax that never appears on the closing statement. Paying cash versus financing works through that trade.
Buyers who finance take a jumbo, usually interest only for a set period. At an assumed 6.5% — an assumption for illustration, not a rate offer — a $4,000,000 loan runs $21,667 a month interest only for fifteen years, then $34,844 a month as the balance amortizes over the fifteen that remain, a step of 60.8%. A third path borrows against a securities portfolio rather than the house, deferring the tax event at the price of a variable-rate line on which a market fall can bring a maintenance call; buy, borrow, die and where the home fits describes that route.
The local costs that change the math
Florida taxes the paper — twice
Most states tax the deed. Florida taxes the deed and the loan. On a deed, the state rate is 70 cents per $100 of consideration everywhere except Miami-Dade, where it is 60 cents, per the Florida Department of Revenue. Miami-Dade adds a surtax of 45 cents per $100 — but the statute bars the surtax on any document conveying only a single-family residence, and it defines that residence to include a condominium unit, a co-op unit and a detached dwelling. So a $5,000,000 condo in Bal Harbour and a $5,000,000 house on Palm Island pay the same deed tax: $30,000. Only property outside the definition — a duplex, vacant land, a commercial parcel — pays the full $1.05.
The loan is taxed separately, and the buyer pays this one. Documentary stamp tax on a recorded mortgage is 35 cents per $100 of the amount secured, with no cap: $14,000 on a $4,000,000 mortgage. The nonrecurring intangible tax adds 2 mills — 0.2% — on each dollar secured: $8,000 more. Financing $4,000,000 in Florida costs $22,000 of state tax at recording, which is one reason cash offers here carry an edge beyond certainty. Florida law makes every party to a document liable; the purchase contract decides who writes each check, and deed stamps are customarily a seller's cost in this market.
No state income tax, and the bill that replaces it
Florida levies no personal income tax, which is part of why this market draws relocating households. What replaces it locally is property tax. Miami-Dade bills combine county, school board, municipal and smaller authorities, and the City of Miami Beach's combined adopted millage for tax year 2025 is 18.7601 mills. On a $5,000,000 home assessed at market, that produces about $93,800 a year. Treat it as an illustration: the assessment resets toward just value at purchase, so a seller's long-held, capped bill tells you nothing about yours, and each authority resets its rate annually.
Wind, flood and the condominium file
On the barrier islands, insurance is an ownership cost, not a formality. A lender requires flood coverage for a home in a designated high-risk flood zone, and wind coverage on the coast is priced by elevation, construction and distance from the water — two similar condos can carry very different premiums. Get the actual figures for the specific address before you set your price, and count them beside the mortgage payment.
Condo buyers face one more file: Florida's post-Surfside building-safety law requires milestone inspections and fully funded structural reserves in buildings three stories and higher. The Miami–Coral Gables market page covers that law in detail; the short version is that an association's engineering and reserve documents now deserve the same diligence as the apartment.
Where the program fits
The program suits a household buying a home of $4M or more, holding $5M or more in assets beyond the home and earning $500,000 or more, that intends to keep the home and would rather commit capital at closing than borrow the maximum. On a $5,000,000 Miami Beach home at the program's standard terms, the household commits half the price at closing: $1,000,000 as the down payment and up to $1,500,000 as the contribution to the financial instrument. The mortgage — $4,000,000, interest only for fifteen years, then principal and interest — is made by a third-party lender, because the program is not a lender, bank, insurance company or government program.
The financial instrument's projected payout is sized to the payment: in the site's $4,000,000 reference case the projected payout of $340,000 a year stands against $334,505 of scheduled payments in years 16 to 30. The payout is projected, not guaranteed; the mortgage runs its full thirty years; designs are tested with no growth credited in their first two years, and the instrument's values are reviewed against the plan every year.
Candidly, it is not for every buyer here. A short hold, or a buyer who wants maximum liquidity elsewhere, is better served by cash or a plain jumbo. The structure fits the buyer who might otherwise pay cash for an island home or a full-floor condo, intends to hold it, and wants the payment in years 16 to 30 to have a designed source. The comparison shows both paths year by year, the calculator runs the structure on the price you have in mind, and the eligibility page states the criteria in full. For the mainland side of this county — the estate streets of Coral Gables — see the Miami–Coral Gables market page.
