Homebuyers

Interested in an Adjustable-Rate Mortgage? How Interest Rates and Rate Caps Work

Over the past few years, homebuyers have been navigating one of the most expensive housing markets in decades.

Mortgage rates in the 6% and 7% range have led some buyers to turn to adjustable-rate mortgages (ARMs). These loans generally offer lower interest rates than fixed-rate loans for the first years of the mortgage. That results in smaller monthly payments and some initial, short-term financial relief.

But those lower payments come with an important caveat. Once the introductory period ends, interest rates can rise to a certain cap or fall depending on current market conditions.

Those interest rate caps are key. There are annual caps, which limit how much your interest rate can increase in a year, as well as lifetime maximums. These lifetime caps prevent your rate from spiking, and keep your monthly mortgage payments in check, even if rates steadily climb.

While ARMs can be valuable tools, it’s important to understand how rate caps work and how they could affect your monthly payments so you can avoid any unpleasant (and potentially costly) surprises.

Why ARMs are back

The appeal of an ARM is straightforward. The initial interest rate is usually lower than the rate on a traditional 30-year fixed mortgage, where the principal and interest portion of your payment is fixed throughout the life of the loan. That difference in interest rates for an ARM can reduce the monthly payment for the first few years of your loan.

These loans made up 8% of all mortgage applications in the week ending Nov. 21, according to the Mortgage Bankers Association.

“They can let people secure a lower rate for at least a little while,” said Adam Hamilton, co-founder of REI Hub, an accounting software company. “But once that temporary period is over, your rate is at the mercy of the market.”

Most ARMs follow a format, such as 5/1 or 7/6. The first number is how long the fixed-rate period will last. In these cases, it’s five years or seven years. The second number is how often the rate will reset after that first period, typically either every year or every six months, based on an index plus a margin set by the lender.

That’s why caps are crucial. They limit how high interest rates can go when your rate adjusts as well as over the life of your loan.

Most ARMs also have an interest rate floor. This is how low rates can fall. So, even if rates are lower in the current market, the interest rate on your loan cannot go below that floor.

For buyers expecting their incomes to rise or who are planning to move before the rate resets, that structure can work well. But if rates go up, their monthly payments could rise.

“Most buyers don’t have a plan for what happens when the introductory period ends,” said Palm Harbor, Fla.-based estate agent Brandon Rimes of Keller Williams Realty. “They treat it like a fixed-rate loan and hope rates stay low, which is a gamble.”

Interest rate caps limit how high interest rates can rise

To prevent dramatic spikes in borrowers’ payments, most ARMs include a set of interest rate caps that determine how much the rate can rise, both at the first adjustment, periodically, and over the life of the loan. This will directly impact the size of the monthly mortgage payments.

Initial adjustment cap: This limits how much the interest rate can increase when the introductory period ends. Many ARMs cap this first jump at two to five percentage points, though some allow up to five points depending on the terms. That’s why it’s so important to understand the loan and what this could mean for your budget before signing on the dotted loan.

For example, a borrower starting with a 5.5% rate on a 7-year ARM with a 4% initial cap could see the rate rise to as high as 9.5% at the first adjustment if market conditions warranted it. It should be noted, though, that interest rates haven’t been over 9% at any point since 1994.

Subsequent adjustment cap: After the first reset, periodic caps limit how much the rate can change at each subsequent adjustment. It’s usually capped by one to two percentage points at a time. Even with these limits, several small increases can add up quickly if market rates are trending up.

Lifetime adjustment cap: This establishes the maximum interest rate a borrower can ever be charged. Most ARMs set the lifetime cap around five percentage points above the initial rate.

In the earlier example, a borrower beginning with a 5.5% interest rate with a 5% cap would never pay more than 10.5%, even if rates rose even higher.

These caps don’t eliminate the risk of higher payments, but they do set a ceiling on how much the loan can ultimately cost.

How rising interest rates affect monthly payments

The cap structure translates directly into potential monthly payment changes, something first-time buyers should pay attention to carefully.

Take a borrower with a $400,000 loan starting with a 5.5% interest rate. Their monthly principal and interest payment is roughly $2,271. If the rate rose to 10.5%, the maximum allowed under many lifetime caps, the monthly payment would climb to about $3,659, an increase of nearly $1,400 a month.

Now, this represents a worst-case scenario, not the default. Mortgage rates would have to shoot up at a historical rate for this to happen.

And many ARM borrowers refinance into other ARMs or fixed-rate loans, sell their homes, or see more moderate adjustments. Still, understanding the outer limits helps buyers determine whether they can absorb potential increases.

“An ARM can work well for someone with a predictable path,” Rimes says. “But if a buyer can’t clearly articulate their exit strategy, refinancing, selling, or a planned income jump, they’re simply hoping for the best. And hope is a terrible financial plan.”

When an ARM makes sense and when it doesn’t

ARMs are not inherently risky, but they are not “set it and forget it” loans. It’s important to understand how interest rate floors and caps can impact future payments and have an exit plan in place just in case. These loans can be a smart option for buyers who:

• Expect significant income growth within the fixed period
• Plan to move or sell before the first adjustment
• Are prepared to refinance once rates fall
• Have strong savings and can handle potential payment increases

Buyers who prioritize stability, have tight budgets, or expect to stay in their home for many years may prefer the predictability of a fixed-rate mortgage.

ARMs: The bottom line

ARMs can offer meaningful savings upfront, which is why they’re resurfacing as interest rates remain high. But they require preparation, an understanding of how rate caps work, and an understanding of how rising rates might affect long-term affordability.

For the right borrower, an ARM can be a strategic tool. For others, the peace of mind of a fixed-rate loan may be worth the higher initial cost.