A home of $4M or more in Greenwich is financed in 2026 almost always with a jumbo mortgage, because the 2026 conforming loan limit for this corner of Connecticut is $977,500 — well under half of what a purchase at this level typically requires. Many buyers here could pay cash, and a visible share do; those who borrow usually structure the loan around assets they would rather not sell. One structure built for exactly that position is The Family Office Mortgage, a privately offered program that pairs a jumbo mortgage with a structured financial product for households buying a home of $4M or more.
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 limit is $832,750 for a one-unit home in most of the country and up to $1,249,125 in high-cost areas, 150 percent of the baseline and the most the statute allows. Connecticut's counties no longer appear on the FHFA's list: the state is now divided into planning regions, and the FHFA publishes a limit for each. Greenwich sits in the Western Connecticut Planning Region, where the 2026 one-unit limit is $977,500. The Greater Bridgeport Planning Region, which covers the rest of Fairfield County, carries the same figure, so $977,500 is the working limit for the county's buyers.
The arithmetic leaves no middle ground. A buyer borrowing half the price of a $4,500,000 home takes a $2,250,000 loan — more than twice the limit. Across the price points that define this market, from around $4,000,000 for a mid-country property to eight figures on the water in Belle Haven, Mead Point or Indian Harbor, every financed purchase is a jumbo, and many are several multiples of the limit.
Because a jumbo cannot be sold to the government-sponsored enterprises, each lender keeps the loan or places it privately and writes its own terms — down payment, reserves, rate structure. How an interest-only jumbo mortgage works covers that loan in detail.
How buyers here actually finance
Three patterns recur.
Cash or near-cash. A cash offer removes the lender from the negotiation, and in a market where many sellers are themselves relocating, certainty counts. The cost is liquidity: once several million dollars are in the house, they come back only through a sale or a new loan, and raising the cash by selling appreciated assets creates a capital gains tax bill that never appears on the closing statement. Paying cash versus financing works through that trade.
A jumbo sized to a large down payment. Buyers who could pay cash often borrow anyway, at 40% or 50% down, cutting the interest cost and keeping capital working. Lenders in this range underwrite the whole household: documented income, the assets that remain after closing, and sometimes pledged assets accepted in place of liquidated ones.
Borrowing against a portfolio. Rather than sell positions, a buyer draws on a securities-based line or pledges investment assets to the lender. The portfolio stays intact and the tax event is deferred; what is added is a variable-rate debt against marketable securities, on which a market decline can bring a maintenance call. Buy, borrow, die and where the home fits describes that route and its risks.
The market's rhythm is set by New York. This is a commuter shoreline: a direct Metro-North run from Greenwich station reaches Midtown Manhattan, and a large share of buyers work in the city or keep a residence there. Listing and closing activity clusters around the school calendar and the early-year bonus cycle, and the deepest pool of buyers arrives with the spring market. A household that keeps capital working in a New York life often wants the same from a home loan here: lower payments early, with principal handled deliberately later. That is where interest-only terms come in.
The local costs that change the math
Property tax. Connecticut property tax is a municipal charge — there is no county tax layer — and state law sets the assessment at 70 percent of a home's market value, with the rate expressed in mills, dollars of tax per $1,000 of assessment. The state's published mill-rate tables put Greenwich at 10.125 for fiscal year 2026-27, against 12.041 the year before. Applied to a $4,500,000 home assessed at 70 percent, the 10.125 rate produces a town tax of about $31,900 a year. Treat that as an illustration, not a quote: the assessor's valuation, not the price paid, sets the bill, and the mill rate is reset when the town adopts its budget each year.
Conveyance tax. Connecticut's real estate conveyance tax is graduated, and at these prices it is one of the largest line items in a sale. For residential property the state share runs 0.75 percent on the first $800,000 of consideration, 1.25 percent on the portion from $800,000 to $2,500,000, and 2.25 percent on everything above $2,500,000, under the Connecticut General Statutes and the Department of Revenue Services' published brackets. On a $4,500,000 sale the state share is $72,250. The municipal share, set by statute at 0.25 percent, adds $11,250, for a total of $83,500 — roughly 1.9 percent of the price; a limited group of municipalities designated as targeted investment communities may add a further 0.25 percent. The tax is collected when the deed is recorded and is customarily a seller's cost, which shapes what a seller nets and how firmly they hold on price.
The deduction limit. Federal law caps the home mortgage interest deduction at interest on the first $750,000 of debt, or $375,000 if married filing separately, for loans taken out after December 15, 2017, per IRS Publication 936. On a loan of several million dollars the deduction reaches only a small share of the interest. Your CPA can state the after-tax cost of a given loan for your case.
Where the program fits
The program is candid about where it belongs in this market. It 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 up front than borrow the maximum. It is a poor fit for a buyer who needs full liquidity elsewhere or expects to sell within a few years.
On a $4,500,000 home at the program's standard terms, the household commits half the price at closing: $900,000 as the down payment and $1,350,000 as the contribution to the financial instrument. The mortgage — made by a third-party lender, because the program is not a lender, bank, insurance company or government program — is $3,600,000, interest only for the first fifteen years and principal and interest for the fifteen after. The rate is an assumption for illustration, not a rate offer: at an assumed 6.5 percent the interest-only payment is $19,500 a month, and in years 16 to 30 the scheduled payment is $31,360 a month. The financial instrument's projected payout is sized to that payment. The payout is a projection, not a guarantee; the mortgage still 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.
The trade is deliberate: $2,250,000 committed at closing, in exchange for fifteen years of the lower payment and a designed source for the later ones. Whether the structure beats paying cash or taking a plain jumbo depends on the household, which is what the comparison and the calculator are for. The eligibility page states the criteria in full. Buyers weighing a Manhattan purchase against this market can read the Manhattan market page for the same math on the other side of the commute.
