Interest-only mortgage paired with an endowment policy intended to accumulate enough value to repay principal at the end of the term.
An endowment mortgage is an interest-only mortgage paired with an endowment policy that is meant to build up enough value to repay the mortgage principal at the end of the term.
This structure became especially associated with the UK mortgage market in the 1980s and 1990s.
Endowment mortgages matter because they separate mortgage servicing from principal repayment. The borrower pays mortgage interest as it arises, but the eventual principal payoff depends on investment performance inside a life-insurance-linked savings vehicle.
That makes the product very different from a Self-Amortizing Mortgage, where the loan balance is reduced through required mortgage payments.
The structure has two moving parts:
the mortgage payment, which covers interest only
the endowment policy contribution, which is supposed to accumulate toward the final payoff
| Structure | Mortgage payment during term | How principal is expected to be repaid |
| — | — | — |
| Self-amortizing mortgage | Principal and interest | Through scheduled loan amortization |
| Interest-only mortgage | Interest only | Later amortization or refinancing |
| Endowment mortgage | Interest only | From endowment policy proceeds at maturity |
A borrower takes a twenty-five-year mortgage and pays only the interest due each month. At the same time, the borrower contributes into an endowment policy that combines investment and life-insurance features. If the policy matures at a high enough value, the proceeds are used to repay the mortgage principal at the end of the term.
An Interest-Only Mortgage only describes the mortgage payment structure. An endowment mortgage adds a separate repayment vehicle tied to an endowment policy.
If the endowment policy underperforms, the borrower can still face a shortfall when the mortgage matures.
Interest-Only Mortgage: The mortgage payment structure inside the product.
ISA Mortgage: Another UK-style interest-only structure that uses an ISA instead of an endowment policy.
Self-Amortizing Mortgage: The contrasting structure that pays principal down directly.
Investment Risk: A core risk because policy returns may fall short of the amount needed.
Shortfall: The gap that appears if the policy value is not enough to clear the mortgage balance.