HELOC Rate Shock: Why a 200 bps Move Hurts More Than You Think

A home equity line of credit (HELOC) is one of the cheapest ways to borrow against your home — until it is not. Unlike a traditional mortgage with a fixed rate, almost all HELOCs are variable. The rate you pay is tied to a benchmark such as the Prime Rate, and when the Federal Reserve moves rates up, your HELOC payment moves up with it, often within a single billing cycle.

The "200 bps" stress test

Banking regulators use a standard exercise called a stress test, where they ask: "If interest rates jumped 2 percentage points (200 basis points) tomorrow, what would happen to this loan?" It is a useful exercise for households too, because HELOC rates have moved by exactly that much — and more — multiple times in the last twenty years.

On a $100,000 HELOC balance at 8 percent interest-only, your monthly interest payment is roughly $667. If the rate moves to 10 percent, that payment becomes $833 — an extra $166 every month, with no change to the principal you owe. Over a year, that is roughly $2,000 in extra interest, paid out of after-tax income.

Why the pain is not linear

Most HELOCs have two phases: a draw period (usually 10 years) where you can borrow and pay interest-only, and a repayment period (usually 10 to 20 years) where the balance has to amortize down to zero. The rate shock during the draw period is uncomfortable. The rate shock when the draw period ends is often devastating, because two things happen at once: principal payments kick in, and they kick in at whatever the prevailing rate is.

A $100,000 balance switching from interest-only at 8 percent to a 10-year amortizing payment at 10 percent goes from $667 a month to roughly $1,322 a month. That is not a stress test result — that is a contractual reality that arrives on a known date.

What to do before you draw

• Run a stress test at +200 bps and +400 bps before you draw the line. If either number is uncomfortable, the line is too large for your income.
• Find out the exact end date of your draw period and put it on a calendar with a 24-month warning.
• Ask whether the lender offers a "fixed rate lock" feature that lets you convert a portion of the balance to a fixed rate. Many do, and it is usually free.
• Treat the HELOC line as borrowing capacity for emergencies, not as monthly cash flow.

Our HELOC Stress Test models the +200 bps shock against your current balance, current rate, and remaining draw period so you can see the payment change before it happens.