Your $40,000 Lump Sum Could Cost You $81,083: Mortgage Recast vs Refinance, Worked Out in Dollars
You just came into $40,000 — a bonus, an inheritance, the proceeds from selling your old home. Your mortgage payment is squeezing your budget, and you want that money to shrink it. Should you recast, or refinance? If your rate is below today's average of 7.11%, recast and keep it. If today's rate is well below yours, refinance — but only if the monthly savings repay the closing costs before you move or refinance again. Both moves lower your payment. They do it in opposite ways, at wildly different prices, and most comparisons skip the number that matters most: what the lump sum itself costs you in interest. Below is the full math on one $300,000 mortgage, so you can run your own numbers the same way. Figures are as of November 2026 unless noted. The One Question That Decides It Compare your rate with today's rate — everything else follows from that single comparison. Freddie Mac's Primary Mortgage Market Survey put the average 30-year fixed mortgage at 7.11% on No...