Why don't all countries allow 50-year mortgages?

1. Funding mismatch: banks fund short, lend long—unless the system is engineered otherwise

Banks in most countries fund mortgages from relatively short-term deposits and therefore prefer adjustable or shorter fixed-rate loans to avoid being stuck with long-term assets funded by short-term liabilities; offering a 50‑year fixed rate would expose lenders to severe reinvestment and duration risk unless they can hedge, securitize, or obtain long-term funding ^{[1] [4]}.

2. Interest‑rate risk and the premium borrowers must pay

Long-term fixed-rate loans carry sizable interest‑rate risk for whoever holds them, and that risk is priced into higher long-term rates or offset by prepayment restrictions; in markets without broad securitization or where prepayment penalties are restricted, lenders demand a material premium for very long fixed terms, making 50‑year mortgages expensive or unattractive ^{[3] [5]}.

3. Securitization and government support create exceptions (U.S., Denmark)

The United States’ 30‑ and longer‑term fixed mortgages became dominant because of secondary‑market institutions and explicit policy choices—Fannie Mae/Freddie Mac and related securitization channels—that move risk from banks to investors and implicitly to government support, a setup most countries don’t replicate; Denmark likewise has institutional features that support long fixed products ^{[2] [1] [6]}.

4. Different policy goals: homeownership subsidy vs. conservative banking

Countries that prioritize stability and bank solvency over maximizing homeownership subsidies tend to favor adjustable or shorter fixed terms; critics argue long fixed-term subsidies can disproportionately benefit wealthier borrowers, and many governments either don’t subsidize long-term fixed borrowing or actively structure systems around alternative social housing and lending approaches ^{[6] [2]}.

5. Tax and consumer‑protection regimes shape demand and supply

Tax rules and rules on prepayment penalties affect demand for long fixed products: in the U.S. mortgage interest deduction historically boosted demand for long fixed loans, and restrictions on prepayment penalties alter pricing; where interest is not tax‑favored or prepayment is tightly regulated, 50‑year loans are less economically compelling ^{[2] [3] [7]}.

6. Market structure and cultural norms: banks holding loans vs. investor markets

Where banks hold mortgages on their balance sheets and link rates to short‑term indices, adjustable and short‑term fixed mortgages predominate; where large investor markets buy standardized loans, long fixed products can be pooled and sold—so the presence or absence of liquid secondary markets determines whether lenders can safely offer multi‑decade fixed terms ^{[1] [4]}.

7. Practical limits, demographic and regulatory frictions

Lenders also confront borrower‑age limits, affordability screening, and differing amortization norms that constrain ultra‑long loans: some countries impose age caps or require proof of retirement income for mortgages that extend past retirement age, and many jurisdictions simply standardize amortizations closer to 20–30 years for prudential reasons ^{[8] [9]}. Wikipedia and industry reporting note 40–50‑year products do exist in pockets where housing costs push demand, but they are exceptions rather than the rule because of the structural factors above ^[5].

Conclusion: a technical, regulatory and political cocktail

The scarcity of 50‑year mortgages is not a single policy choice but the outcome of interlocking realities—funding and duration risk, the presence or absence of securitization and government backing, tax and consumer‑protection frameworks, and national priorities about housing finance—so most countries simply lack the combination of market infrastructure, policy commitment, or appetite to make ultra‑long fixed mortgages common ^{[1] [2] [3]}.