01The break-even month is the whole decision
Divide your closing costs by the monthly savings and you get the number of months required to recover the cost. If closing costs are $4,800 and you save $215 a month, break-even is month 23. Stay longer and you win; sell or refinance again sooner and you lose.
The rule of thumb is that break-even should land inside your expected holding period with margin — usually under 30 months for a rate-and-term refinance. If break-even is 48 months and you might move in three years, the math does not support the loan.
Rolling closing costs into the loan feels free but is not: it raises the balance and the interest you pay, and it lengthens break-even. Compare a rolled loan against a paid-upfront loan side by side.
02Payment drop versus interest saved
Restarting a 30-year clock lowers the payment even at a lower rate, because you stretch the remaining balance over more years. A borrower 8 years into a 30-year loan who refinances to a new 30-year at a lower rate may see a modest payment drop — and pay more total interest than if they had stayed put.
Always check both numbers. If the goal is total interest, shorten the term to 20 or 15 years even if the payment barely moves. If the goal is monthly cash flow, extending the term is acceptable, but understand you are buying breathing room rather than savings.
- Compare the interest remaining on the current loan with total interest on the new loan.
- A refinance that shortens the term can raise the payment while still saving six figures.
- Watch for a new prepayment penalty or an extended escrow shortage.
03Refinance versus recast
A recast is not a new loan. You pay a lump sum toward principal, the lender re-amortizes the remaining balance over the original end date, and your payment drops. There is no credit check, no appraisal in most cases, and the fee is usually $250 to $500.
Recasting is the right tool when you have a windfall and want a lower payment without touching your rate. It cannot lower your interest rate, which is where refinancing earns its keep. If your rate is already competitive, recast; if it is a point above market, refinance.
04Points, mortgage insurance and the ARM you are leaving
A discount point costs 1% of the loan and buys a lower rate. Whether it pays is the same arithmetic as the refinance itself: divide what the point costs by what it saves each month. On a $336,000 loan a point is $3,360; if it buys 0.25% it saves about $56 a month, so it needs sixty months to pay for itself — fine if you stay, expensive if you move.
Refinancing also resets your mortgage insurance. A loan that started at 90% loan-to-value can refinance at 78% if the home has appreciated or the balance has been paid down, and private mortgage insurance then stops entirely. That saving belongs in the break-even, not in a footnote, because a $170 monthly premium dwarfs a quarter-point rate cut.
If you are leaving an adjustable-rate loan, price the ceiling you are escaping. A loan that started at 5.5% with a 2% initial and a 5% lifetime cap could have reached 10.5% — the fixed loan must be compared with that payment, not with the teaser.
- Points and closing costs are both cash at closing; treat them as one number.
- PMI is charged only while the new loan is above 80% of the home value.
- An ARM conversion is a risk purchase: you are paying for certainty, not for a lower payment.
05Cash-out refinancing and its real cost
A cash-out refinance replaces your mortgage with a larger one and hands you the difference. It is often used for renovations or debt consolidation, and it resets the pricing on your entire balance — including the portion you had already been paying at a lower rate.
Because the rate applies to the whole loan, comparing a cash-out refinance to a HELOC comes down to blended cost. If your existing rate is meaningfully below market, taking a second lien preserves it. If your rate is at or above market, one consolidated loan is usually simpler and cheaper.