What is a fixed-rate HELOC?

A standard HELOC carries a variable interest rate, typically set as the Prime Rate plus a margin the lender sets based on your credit and loan-to-value ratio — meaning your payment can rise or fall as the Prime Rate moves with Federal Reserve policy. A "fixed-rate HELOC" (sometimes called a rate-lock option or a fixed-rate advance) is a feature some lenders offer that lets you convert all or a portion of your outstanding balance to a fixed rate for a defined term, insulating that locked portion from future rate moves while any remaining unlocked balance stays variable.

How the lock actually works

Typically, you draw funds on the HELOC as usual during the draw period, then request that some or all of the outstanding balance be converted to a fixed rate for a set repayment term — the locked portion then behaves like a standalone installment loan, with a fixed payment, layered on top of your still-open credit line. Not every lender offers this feature, and terms vary: some let you lock multiple times during the draw period, others allow only one lock per line, and some charge a small conversion fee or a slightly higher rate for the fixed portion compared to the current variable rate.

Fixed-rate HELOC vs. a traditional home equity loan

• Home equity loan: a lump-sum, fixed-rate, fixed-term installment loan from the day you close — you get all the money at once and start repaying immediately.
• Fixed-rate HELOC: a hybrid — you still have an open, revolving credit line for the unlocked portion (draw, repay, redraw as needed), with the option to fix the rate on some or all of what you've drawn.
• Standard variable HELOC: the entire outstanding balance floats with the Prime Rate, offering maximum flexibility but no protection from rate increases.

The trade-off

Locking a portion of your HELOC balance protects you from rate increases on that amount, but it typically reduces flexibility on that specific portion — many lenders don't let you freely pay down and redraw a locked balance the way you can with the variable portion, since it's now functioning like an installment loan. Ask any lender offering this feature exactly how the locked portion behaves: whether extra payments reduce the locked balance, whether you can re-lock at a new rate later, and whether there's a fee to lock or unlock.