It mostly depends on the rate on your existing first mortgage, because that is what you are protecting. A HELOC (home equity line of credit) borrows against your equity without touching the first mortgage, so it shines when you have a low locked-in rate you do not want to disturb. - Low first-mortgage rate: a HELOC lets you pull cash while the great rate stays intact. The trade is that HELOCs usually carry variable rates tied to short-term benchmarks, so the line's cost moves as the Fed moves, in either direction. - Higher first-mortgage rate: the calculus flips. Refinancing the whole loan often beats layering a second lien on top, because there is no low rate to sacrifice. FHA and VA borrowers have an extra edge here. Their streamline refinances can lower the rate with no appraisal, and the standard versions (FHA's non-credit-qualifying streamline and the VA IRRRL) skip income documentation too, which makes them faster and cheaper than a full refinance and often better than bolting on a HELOC. Rates on all of these move, so the actual numbers settle it, and that is a quick thing to run together.