HELOC rates follow the Fed almost directly, because nearly every home equity line is tied to the Prime Rate, and Prime moves in lockstep with the federal funds rate. When the Fed cuts, Prime drops by the same amount and your HELOC rate follows. When the Fed hikes, the line moves the other way. That is the deal with a variable second lien: the rate falls in a cutting cycle and rises in a hiking cycle, and you carry that exposure the whole time. The timing is quick but usually a billing cycle behind. Most HELOCs bill on roughly a 30-day cycle, and your line agreement spells out which day of the month the index is read. So after a Fed move, expect the new rate to show up starting with your next billing cycle. Check your specific agreement for three things: the index, the margin added on top of Prime, and the reset date. One practical implication for structuring. When rates are elevated and expected to ease, a variable HELOC can be attractive because the cost should drift down over the life of the line. When rates are already low, a fixed-rate second can be the safer structure, since a variable line would mostly have room to rise. Nobody can promise the Fed's path, so weigh the structure against your own timeline and how long you expect to carry the balance, and pick the version you could live with if the path surprises everyone.