Yes, on a standard refinance you would generally have to cover the gap yourself, because the new loan is limited by loan-to-value against the current appraised value. A refinance is sized off an appraisal. If your home's value has fallen and you owe more than your program allows against the appraised value, you would have to pay the balance down to qualify. (A side note on timing: some programs, mainly cash-out refinances done within the first 6 to 12 months of ownership, cap the value used at your original purchase price. A few years out, the appraisal is what governs.) Two exceptions matter: - FHA Streamline and VA IRRRL. FHA's non-credit-qualifying streamline requires no appraisal and no income re-verification, though it must pass a net tangible benefit test. The VA IRRRL requires no appraisal and no income verification in the ordinary case. A drop in value would not block either one. - Underwater-relief programs. After the last downturn, Fannie Mae and Freddie Mac created programs that let qualifying underwater borrowers refinance to lower rates despite lacking equity. That specific relief has ended, though a future downturn could bring something similar. On protecting yourself: there really is no product that insures your equity position the way mortgage insurance protects the lender. The real protection is upstream. Buy for the right reasons, with a time horizon long enough that a temporary dip never forces you to refinance or sell at the wrong moment. Illustratively, buying at a 6% rate hoping to refinance at 4% later, then seeing a 15% value drop in between, could leave you bringing cash to the table. Time horizon matters more than trying to time the rate.