The piece most of this discussion misses is that paying down a mortgage is a one-way door, and that is a bigger deal than the return comparison everyone argues about. A dollar you put into extra principal is gone. You cannot get it back without selling the house, refinancing, or opening a HELOC, and if you need it in a year when rates are higher than yours, you are effectively buying your own money back at the new rate. A dollar in a taxable brokerage account is available in three days. Same dollar, completely different optionality. Three other things worth knowing before you decide. Extra principal does not lower your payment. On a standard fixed mortgage, paying extra shortens the term. Your required monthly payment stays exactly the same. So if the appeal of paying it down is "I will have more breathing room each month," that is not what happens, and people are genuinely surprised by this. Ask your servicer whether they will recast, meaning re-amortize the loan after a lump sum so the payment actually drops. Many will for a modest fee, but you usually have to ask for it by name. Check whether you are getting anything from the mortgage interest deduction. With the standard deduction where it is, plenty of households do not itemize at all, which means the interest deduction is worth exactly nothing to them. If you have been mentally discounting your rate for the tax benefit and you take the standard deduction, your real rate is your rate. Your CPA can tell you in one look at last year's return. A low fixed rate behaves like a hedge. It is one of the few household liabilities that gets cheaper in real terms as prices rise, because you repay it with dollars worth less than the ones you borrowed. That is a real, if unglamorous, argument for keeping it. If I were sitting across from you, I would ask this instead of the return question: is your emergency fund fully funded, is the retirement match captured, and is there any higher-rate debt anywhere? Because the answer to your $200 question changes completely depending on those three. Extra principal on a low-rate mortgage while carrying a credit card balance or leaving a 401(k) match on the table is the one clearly wrong version of this. I am a real estate professional, not a financial advisor or a CPA, and this is a personal finance question with real tax consequences, so I am not going to tell you which one to pick. A fee-only advisor who charges by the hour, not by assets under management, can run this against your actual numbers in a single session. One note for anyone reading this thread later: it was asked in April 2023, when the gap between a pandemic-era mortgage rate and what you could get risk-free elsewhere looked very different than it does now. Rerun the comparison with current numbers rather than the ones in the older answers. I am Zoltan Peresztegi, and I work in Los Angeles and the South Bay, so Alexandria is not my market, but if you want an introduction to a strong Northern Virginia agent, just ask. Zoltan


