A home of $4M or more in Highland Park or University Park — the Park Cities, two independent municipalities bordered on all sides by the City of Dallas — is financed in 2026 almost always with a jumbo mortgage, because the 2026 conforming loan limit for Dallas County is $832,750, the national baseline and a fraction of what these homes sell for. Buyers here bring far more than a standard down payment: many pay cash or close to it, and those who borrow tend to structure the loan around capital 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 at this level.
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 it is $832,750 for a one-unit home in most of the country, rising to $1,249,125 in high-cost areas. The FHFA's county list places Dallas County at the baseline, as it does all 254 Texas counties; none reaches the ceiling that coastal California counties sit at.
The arithmetic leaves no middle ground. A buyer who borrows 80 percent of a $4,500,000 home takes a $3,600,000 loan — more than four times the county limit. From the $4M-and-above segment to the Preston Hollow and Turtle Creek estates, every financed purchase here is a jumbo, most several multiples of the limit — the range lenders informally call super-jumbo.
The homes themselves concentrate in a small set of neighborhoods: the Park Cities, and the nearby Dallas estates of Preston Hollow, Bluffview and Devonshire. Inventory is thin and many sales are arranged quietly rather than broadly marketed. 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 thin market sellers value the certainty. The cost is liquidity: money in the house comes back only through a sale or a new loan, and raising it by selling appreciated assets creates a federal 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; in exchange comes 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.
Interest-only terms are common within these: pay only the interest for a fixed period and decide deliberately what repays the principal, rather than letting the loan decide.
The local costs that change the math
Property tax. Texas has no state property tax; the Comptroller's office does not collect property tax or set rates. Every rate is local, set by each taxing unit — town or city, school district, county, hospital district, community college district — and homes are appraised at market value by the county appraisal district. The Comptroller's 2025 statewide list of tax rates, the most recent published, shows the units that stack on a Park Cities address: the town (about 0.2% in both Highland Park and University Park), Highland Park ISD (about 0.83%), Dallas County (about 0.22%), the hospital district (about 0.21%) and the community college district (about 0.11%). Combined, that is a rate near 1.6% of market value — roughly $71,000 a year on a $4,500,000 home before exemptions. A City of Dallas address stacks higher — the city's rate (about 0.70%) plus Dallas ISD (about 0.99%) and the county units total about 2.2%. These are comparatively high property taxes by national standards — the trade a state makes when it levies no income tax.
Homestead relief is modest at these prices: school districts must exempt $140,000 of a homestead's value from school tax, applied for with the appraisal district — roughly $1,200 a year at the current school rate.
Transfer tax. None. The Comptroller's office administers the state's complete A-to-Z list of taxes and fees, and no tax on the transfer of real property appears on it. A closing in Highland Park carries the county's deed recording fees, not a percentage of the price. The same purchase in Manhattan carries New York State and City transfer taxes and a mansion tax; here there is no transfer tax at all.
No state income tax. The Comptroller states it directly: Texas has no state income tax. A gain on this home, when it is eventually sold, is not taxed at the state level; federal capital gains tax still applies.
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 this size the deduction reaches only a small share of the interest; your CPA can state the after-tax cost 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 up to $1,350,000 as the contribution to the financial instrument — $2,250,000 in total, against $4,500,000 for an all-cash purchase and $900,000 for a traditional 20% down payment. Where the instrument needs less, more goes to the down payment. 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%, the interest-only payment is $19,500 a month, in years 16 to 30 the scheduled payment is $31,360 a month, and a traditional 30-year loan of the same amount at the same assumed rate would run $22,754 a month from the first month. The financial instrument's projected payout is sized to that later payment — 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: capital committed at closing, in exchange for fifteen years of the lower payment and a designed source for the later ones. The team behind the program has done hundreds of transactions. 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, and what a Family Office Mortgage is explains the structure for a household meeting them for the first time.
