Bach calls "buying a home is the escalator to wealth in America." And, he suggests, if you want to retire early, pay off your mortgage early, too. "I can tell you, having been a financial advisor at Morgan Stanley, my clients who retired at 50 years old, the secret was: They had paid their mortgage off early," he tells CNBC Make It.
To make that happen, Bach advises taking out a 30-year mortgage with the intention of eliminating it in 15 to 20 years. Then, increase your payments by 10 percent and let your bank know that you want the extra money applied to the principal, not the interest.
"If you keep this up, you'll wind up paying off your 30-year mortgage in about 25 years," he writes in "Smart Couples Finish Rich." "Increase your monthly payment by 20 percent, and you'll have that mortgage retired in about 22 years."
Even if you don't plan to retire in your 50s, Bach says, paying off your mortgage early can save you tens or even hundreds of thousands of dollars in interest.