When Does It Make Sense to Refinance a Mortgage?

Refinancing a mortgage means replacing your existing home loan with a new one, typically at a lower interest rate. Done at the right time and for the right reason, it can save tens of thousands of dollars. Done at the wrong time, or without doing the math, it can quietly cost you money by resetting the loan clock and pushing more of your early payments back into interest.

How the math works

Two questions: what are the closing costs, and how much lower is the monthly payment? Divide the closing costs by the monthly savings to find the breakeven point in months. If closing costs are $6,000 and the new payment saves $200 per month, the breakeven is 30 months (2.5 years). If you plan to stay in the home longer than the breakeven, refinancing likely saves money.

The interest-rate rule of thumb

The old rule "refinance when rates drop 1 percent below your current rate" is a rough shorthand. A more precise version: refinance when the monthly savings times the number of months you expect to stay in the home clearly exceeds the closing costs. On a small loan balance, even a 1.5 percent rate drop may not clear the breakeven. On a large loan balance, even 0.5 percent can be worth it.

Term matters as much as rate

Refinancing to a lower rate on the same remaining term is a straightforward win if you clear the breakeven. Refinancing to a longer term (say, resetting a 30-year loan back to another 30 years) usually lowers the monthly payment but increases total interest paid, sometimes dramatically, because the loan clock restarts. If you have already paid off 8 years of a 30-year mortgage, refinancing into a fresh 30-year loan effectively adds 8 years of interest.

A better approach when you want the rate benefit but not the reset: refinance into a term matching or shorter than your remaining term. Many lenders offer non-standard terms (25, 20, 15 years) that fit this.

Cash-out refinancing

A cash-out refinance is a new loan larger than your current balance, with the difference paid to you in cash. This is genuinely useful for high-value purposes (home improvements that add value, consolidating meaningfully higher-interest debt into a mortgage-rate loan), but risky when used to fund lifestyle spending. Turning unsecured debt into home-secured debt without changing behaviour is a fast path to losing the house.

When not to refinance

Skip refinancing if you plan to move within a couple of years, if you cannot clear the breakeven, if you would extend the loan term meaningfully, or if your credit score has fallen since the original loan (which usually means a worse rate offer). Also skip if the paperwork burden and short-term credit-score dip would interfere with a near-term goal like buying another property.