While the current low-yield environment has presented significant challenges to retirees trying to generate retirement income, the upside is that low yields have also driven down borrowing costs to record lows. As a result, retirees are increasingly deciding that perhaps keeping a mortgage and not paying it off is a good idea after all; with the average long-term return on stocks being significantly higher than today's 30-year mortgage rates, an inexpensive mortgage becomes a strategy to leverage the household balance sheet and boost the amount and sustainability of retirement income.
Yet the decision to keep a mortgage in retirement is not without risk. There's a danger than equities won't perform as expected, and fail to generate a return in excess of the borrowing cost over a relevant time period. And even if the returns do ultimately add up, the ongoing payment obligations for a traditional mortgage create a "sequence of returns" risk for the retiree, where withdrawals to handle the mortgage payments could so deplete the portfolio during an extended period of bad returns that there may not be enough money left over for when the good returns finally arrive.
From this perspective, retirees should perhaps consider the reverse mortgage instead. While such loans have been relatively unpopular - due in part to their high costs, and because they're often viewed as a borrowing option of last resort - the reality is that the lack of any cash flow obligations for a reverse mortgage actually allows it to eliminate the sequence risk from the mortgage-in-retirement strategy. In fact, over a long period of time, using a reverse mortgage in retirement can result in materially greater wealth when equities do perform as desired, as the reverse mortgage maintains a greater amount of household leverage, even while reducing the exposure to the impact of an unfavorable sequence of returns.
In the end, there are still a few caveats to the strategy - most notably, that reverse mortgages still tend to have higher upfront and ongoing borrowing costs (though the gap is narrowing), and that lending limits may constrain the usefulness of the strategy for affluent clients (who are often most interested in increasing household leverage as a retirement strategy). Nonetheless, the fact remains that for those who truly do wish to engage in the mortgage-in-retirement strategy, the reverse mortgage may be the most effective way to execute it.