A mortgage you don’t have to pay off, and can leave to your heirs, sounds almost too good to be true. In fact it’s a variation on the interest-only mortgage which has been around for a long time.

The real point of this shakeup in the industry is that in passing the debt onto your children you slash the amount of inheritance tax they might have to pay.

In recent years house prices have risen so fast that the threshold of death duties — £285,000 ($536,000) per estate — is being exceeded by many ordinary middleclass homeowners. The Chancellor seems in no hurry to fix the problem and so the mortgage industry is attempting to fix it for him.

This type of mortgage is very popular in countries like Switzerland and Japan, where the populations are known for their thrift.

The Kent Reliance Building Society is launching its version this week under the name, Inter-Generational Mortgages. Chief Executive Mike Lazenby said they’d thought of calling it the Deathbed Mortgage but thought “it would be a bit morbid.”

This is a good idea if an elderly parent wants to leave a big-ticket house to the children without death duties. Although in theory the mortgage could be passed down indefinitely, it’s unlikely to happen because the family would pay a lot of interest without ever owning the property.