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Short Summary
Main recommendation: Graham Stephan shares his personal view that, on a 30-year mortgage, it is usually mathematically better to make only the minimum payments and invest the difference rather than paying the loan down early, with exceptions he notes for very high interest rates and for people who may not stick to investing. He illustrates this with a $400,000 loan at 4.2% over 30 years, where investing the extra $1,050 per month at a 7.5% return ends up roughly $433,000 ahead of an early payoff.
Key Points
- The early-payoff math is driven by three factors: the mortgage interest tax deduction (about 23% reduction in effective interest for a 23% bracket), inflation (about 2% per year), and the opportunity cost of the extra money.
- After tax and inflation, the 4.2% loan's effective cost is about 1.23%, while the stock market has historically averaged about 7.5% after inflation.
- Under his example, the early-payoff scenario ends with a paid-off home plus about $1,000,000 invested, versus a paid-off home plus about $1,433,000 invested for the minimum-payment investor.
- He says paying off early can make sense if the interest rate is above about 6%, since the guaranteed return then becomes competitive with investing.
- Paying off early offers peace of mind, a freed-up monthly payment, and security of owning the home outright regardless of job loss or market crashes.
Details Worth Noting
- Concrete instructions: Compute your effective mortgage rate by subtracting your income tax bracket percentage from the interest rate (for example, 4.2% minus 23% of that rate gives about 3.23%), then adjust for about 2% inflation (about 1.23%). Compare that figure against the return you expect from investing, using about 7.5% as the historical stock market average the speaker cites. Keep the minimum mortgage payment and invest the difference (in his example, $1,050 per month) into an S&P 500 index fund, and only do this if you will actually invest the money rather than spend it.
- The $400,000 example uses a $1,956 monthly payment and $304,000 total interest; the $3,000 monthly payment pays off the loan in 15 years.
- The mortgage interest deduction is described as applying to the first $750,000 of mortgage debt on a primary residence, and 100% of interest on investment properties against rental income.
- The speaker notes that the early-payoff advantage of guaranteed return depends on the borrower's discipline; he says most people will likely not invest the difference.
- He states he would personally pay down a loan above 6% and invest with a loan under about 6% — though he frames this as his own preference, not universal advice.
Bottom Line
For most people with a long-term, moderate-rate mortgage, the speaker's math favors investing the difference, but the answer depends on the rate, tax situation, and whether you will consistently invest the extra money.
