Should you pour extra cash into your mortgage or send it to a brokerage account? The answer depends on your note rate, your alternatives, and how you value liquidity. Both paths build wealth—just through different mechanisms.
The guaranteed return of prepayment
Every extra dollar you pay toward principal saves you interest at your mortgage rate, compounded over the remaining term. If you carry a 6.5% note, each additional payment effectively earns 6.5% per year by eliminating future interest charges. That return is certain—you know exactly what you avoid paying. These figures are illustrative; rates and products are subject to change and this is not a commitment to lend.
On a 300,000 loan at 6.5% over thirty years, an extra 200 monthly payment cuts roughly four years off the term and saves about 48,000 in interest. The math is straightforward: the higher your rate, the more compelling the prepayment case looks on paper.
Market alternatives and break-even logic
The counterfactual is investing that same 200 each month. Historically, diversified equity indexes have returned around seven to ten percent annualized over long horizons, though with year-to-year volatility. If your after-tax investment return exceeds your mortgage rate, the spreadsheet says invest. If it falls short, prepay.
The break-even rate is where the two paths converge. A borrower at 6.5% who expects eight percent from stocks sees a net 1.5 percentage-point advantage in the market—on average, over decades, and ignoring sequence risk. A borrower at 7.5% who expects the same eight percent sees only half a point of upside and may prefer the certainty of debt reduction.
Consult a CPA or attorney; this is not tax or legal advice.
Liquidity, risk tolerance, and the Alliance take
The math alone doesn't settle it. Mortgage principal is illiquid—you can't spend equity without refinancing or selling. An investment account remains accessible for emergencies, college tuition, or pivoting to opportunity. That optionality has real value, especially early in a career or when cash reserves are thin.
Risk tolerance matters too. Market returns are probabilistic; prepayment returns are contractual. If a portfolio downdraft would keep you up at night, the emotional dividend of a shrinking mortgage balance may outweigh a few basis points of expected return.
Our take: run both scenarios in parallel when possible. Maintain an emergency fund, max any employer match in your retirement plan, then split surplus cash between accelerated principal and taxable investments. The blend captures some market upside while steadily de-risking your balance sheet. Refinancing to a lower rate when conditions allow can also tilt the equation back toward investing.
Start an application if you'd like to explore how a lower rate changes your prepayment math, or use our calculators to model different payment strategies side by side.