Yes. If the Federal Reserve raises the federal funds rate, your HELOC payment goes up, usually within one to two billing cycles. Your fixed first mortgage does not move at all. That split confuses a lot of Arizona homeowners, and it matters right now because markets have been pricing roughly 90% odds of a quarter point hike at the September 2026 Fed meeting, which would be the first increase since 2023.

Here's the short version for Scottsdale and Phoenix homeowners carrying a line of credit: a quarter point hike is not a crisis, but it is a signal. And if you've been carrying a balance on a HELOC you opened when prime was falling, the math you ran back then is no longer the math you're living with.

How the prime rate actually sets your HELOC payment

Your HELOC rate is built from two pieces: the prime rate plus a fixed margin your lender assigned at closing. The margin never changes. Prime does.

The prime rate tracks the Fed funds rate almost perfectly, sitting about 3 percentage points above it. When the Fed moves a quarter point, major banks reset prime by the same quarter point, typically the next business day. The Wall Street Journal prime rate has been 7.50% since mid 2025, after four quarter point cuts walked it down from a peak of 8.50%.

So if your HELOC is prime plus 1%, you're paying 8.50% today. After a quarter point hike, you're at 8.75%. Your lender applies it at your next statement, not instantly.

What a quarter point actually costs on a real Arizona balance

The dollar impact depends entirely on your drawn balance, not your credit limit. Unused line costs you nothing.

On a $75,000 drawn balance during an interest only draw period, 8.50% runs about $531 a month. At 8.75% that becomes roughly $547. You're looking at about $16 more per month.

On a $150,000 balance, the same quarter point moves you from about $1,063 to about $1,094, or roughly $31 more per month.

That's survivable. The problem is that hikes rarely arrive alone. Three quarter point hikes over a year would put that $150,000 balance up about $94 a month, and a HELOC that rolls out of its draw period into full principal and interest repayment can double the payment on its own, independent of any Fed move. Plenty of Valley homeowners who opened lines in 2021 and 2022 are hitting that repayment conversion right about now.

What a Fed hike does not change

Your 30 year fixed first mortgage payment. Not one dollar. If you locked at 5.25% in 2021, you still have 5.25% no matter what the Fed does for the next 29 years.

It also does not directly set new mortgage rates. The 30 year fixed follows the 10 year Treasury and mortgage backed securities pricing, which respond to inflation expectations more than to any single Fed announcement. Freddie Mac has had the 30 year fixed hovering near 6.76%, a one year high, and that move happened on bond market repricing well before the Fed voted on anything.

What does move with prime: HELOCs, most home equity lines, credit cards, and a lot of small business and personal lines of credit. If you're carrying balances across several of those, the combined monthly impact is bigger than the HELOC math alone suggests.

Three moves Arizona homeowners have right now

First, check whether your HELOC has a fixed rate conversion option. Many lenders let you carve out part or all of your drawn balance and lock it at a fixed rate mid draw, sometimes at no cost. Most homeowners never read that far into their agreement. Call your servicer and ask directly.

Second, look at whether rolling the line into a fixed second mortgage or a cash out refinance makes sense. That trade only works if the blended math beats what you're paying now, and with first mortgage rates in the mid to upper 6s, a homeowner sitting on a 3% or 4% first usually should not touch it. Someone who bought in 2023 or 2024 at 7% or higher is in a very different position.

Third, prioritize paying the variable balance down before anything fixed. A dollar aimed at an 8.75% variable line does more for you than a dollar aimed at a 5% fixed first.

Why the equity picture matters more in Phoenix this year

Metro Phoenix has shifted meaningfully toward buyers. Active listings are running well above recent years, the median listing price in Phoenix is around $485,000, and in Scottsdale roughly 76% of active listings have taken a price cut this fall, with a median around $945,000. You can see how that leverage is playing out in listings across the Valley on Homes.com.

Softer values matter for equity borrowers. A HELOC is underwritten off a combined loan to value ceiling, and if Valley values keep easing while your balance stays flat, your available credit can shrink. Some lenders will freeze or reduce a line when values drop enough. If you're planning to draw on a line for a renovation or a business need in the next year, pulling that draw sooner rather than later is worth considering. Browse what's actually moving in the Valley at Arizona Luxury Property Search.

What to do this week

Pull your HELOC statement and find two numbers: your margin and your current drawn balance. Those two figures tell you exactly what any Fed move costs you. Then decide whether you want that exposure floating for the next two years or locked down. There's no universal right answer, and anyone who tells you there is has not looked at your first mortgage rate. Our team at Pillar Mortgage Group runs that comparison for Arizona homeowners every week.

The draw period cliff nobody plans for

Rate increases are the small problem. The end of your draw period is the large one, and it arrives on a schedule you agreed to years ago.

Most HELOCs run a ten year draw period where you can borrow and pay interest only, followed by a twenty year repayment period where the line closes and you amortize the balance. The payment change at that boundary is not gradual. On a $150,000 balance at 8.75%, interest only is roughly $1,094 a month. Fully amortizing that balance over twenty years takes it to about $1,326, and that is before any further rate movement.

A lot of Arizona HELOCs written during the 2016 to 2019 stretch are hitting that boundary now. If yours was opened in that window, find your draw end date this week. It is on your statement and in your original agreement.

You have three real options and they all take lead time: refinance the line into a fixed rate product, pay the balance down before the repayment period starts, or negotiate a new HELOC with a fresh draw period, which is easier to do while your line is still performing than after the payment jumps.

The Consumer Financial Protection Bureau covers how the two periods work and what your lender is required to disclose. Worth reading alongside your actual agreement, because terms vary more between lenders on HELOCs than they do on first mortgages.

Phoenix homeowners have an advantage here that they did not have a few years ago, which is equity. That gives you options. It also means a cash out first mortgage is worth pricing even at today's rates if the HELOC balance is large enough relative to the first.

Run your own numbers

If this is on your plate right now, a few things worth reading next: rolling a HELOC into a fixed rate, cash out refinance versus HELOC, and home equity loan versus cash out. For the wider picture, Our loan programs page and the process page cover what we can actually do and what the process looks like. And if the plan involves buying rather than staying put, current listings are at Arizona Luxury Property Search.

The Consumer Financial Protection Bureau explains how a variable HELOC rate is built from prime plus a margin, and the Federal Reserve publishes the federal funds target directly so you can see the move for yourself rather than through a headline.

Honest caveat: rolling a HELOC into a fixed first mortgage is not automatically the answer. If your first mortgage is at 3.5%, refinancing the whole balance to 7% to fix a $31 increase is a terrible trade. The move usually only makes sense when the HELOC balance is large relative to the first, or when the draw period is ending.

Frequently asked questions