Adjustable-Rate Mortgages (ARMs) Explained: What You Need to Know Before You Sign

If you’ve been loan shopping, you’ve probably seen the term ARM pop up next to a lower rate than everything else on the page. That’s an adjustable-rate mortgage, and it’s a question we get asked often at Gershman Mortgage especially once someone sees that lower number and wants to know what the catch is.

Here’s the short version: an ARM starts with a lower, fixed rate for a set number of years. After that, the rate can go up or down based on the market. The question isn’t whether an ARM is good or bad. It’s whether it fits how long you plan to keep the loan and how much rate movement you can handle.

Let’s break down how these loans work.

What Is an ARM Loan?

An ARM is a mortgage with an interest rate that changes over time instead of staying the same for 30 years. Most ARMs start with an initial period where the rate is locked in, then switch to adjusting once a year.

FHA offers a few different ARM options, and they’re built around how long that initial locked-in period lasts:

• 1-year ARM: Rate adjusts every year, starting right away
• 3-year hybrid ARM: Rate is fixed for 3 years, then adjusts annually
• 5-year hybrid ARM: Rate is fixed for 5 years, then adjusts annually
• 7-year hybrid ARM: Rate is fixed for 7 years, then adjusts annually
• 10-year hybrid ARM: Rate is fixed for 10 years, then adjusts annually

“Hybrid” just means the loan is part fixed, part adjustable. You get a stretch of predictable payments up front, then the rate starts moving with the market.

Conventional ARMS work the same way in concept, but the exact cap numbers are specific to FHA loans. If a loan officer quotes you a conventional ARM, ask for the loan’s specific cap structure. It is usually similar, but it isn’t guaranteed to match FHA’s numbers exactly.

How Does an Adjustable-Rate Mortgage Work?

Once your fixed period ends, your lender recalculates your rate once a year based on a market index, plus a set margin. That new rate can’t move however it wants. It’s boxed in by the caps below. So your payment can go up or down each year, but it moves in limited, predictable steps instead of jumping all at once.

What Are Rate Caps, and Why Do They Matter?

This is the part that protects you, and it’s the part most people skip over.

Rate caps put a ceiling (and a floor) on how much your interest rate can move. There are two kinds:

Annual cap: Limits how much your rate can change, up or down, in any single year once the adjustable period kicks in.

Life-of-the-loan cap: Limits the highest (and lowest) rate you can ever pay for as long as you have that mortgage, period.

So even if market rates spike, your rate can only climb so far, so fast. That’s the whole point of the cap structure. It keeps a bad year in the market from turning into a payment you can’t afford.

According to HUD’s guidelines on Section 203 ARM mortgages, here’s how the caps break down by loan type:

ARM Type	Annual Cap	Life-of-Loan Cap
1-year & 3-year ARM	1 percentage point	5 percentage points
5-year ARM	1 point (or 2 points, depending on the loan)	5 points (or 6 points)
7-year & 10-year ARM	2 percentage points	6 percentage points

Notice the pattern: the shorter the initial fixed period, the tighter the cap. That makes sense. A 1-year ARM starts adjusting almost immediately, so it needs a smaller annual cap to keep things predictable. A 10-year ARM has already given you a decade of stability, so it allows a little more room once it starts moving.

A Real Example: Fixed-Rate vs. ARM

Let’s say you’re borrowing $350,000 on a 30-year term, and a Gershman Mortgage loan officer is walking you through both options. Here’s how a fixed-rate loan and a 5-year ARM might compare in the first few years.

Fixed-rate loan (example rate: 7%)

• Monthly principal and interest: about $2,328
• That payment stays the same for all 30 years

5-year ARM (example starting rate: 6.25%)

• Monthly principal and interest for years 1-5: about $2,155
• That’s roughly $173 less per month while the rate is locked in

Now let’s say year 6 has arrived and market rates have gone up. With a 1-point annual cap, your new rate can’t jump past 7.25%, even if the broader market is higher than that. Your payment would adjust to reflect the new rate, but it can’t blow past what the cap allows.

On that same $350,000 loan, a 7.25% rate over the remaining 25 weeks works out to about $2,361 a month, roughly $33 more than the fixed-rate payment would have been the whole time. Even in that worse-case scenario, you’d have already banked five years of lower payments before it happens.

If rates had dropped instead, your rate could adjust too. That’s the flip side people forget about. ARMs aren’t a one-way street.

The real question to ask yourself: will you still have this loan in year 6? If you’re planning to sell, refinance, or pay it off before the fixed period ends, you get the lower payment now without ever touching the adjustable part. If you’re planning to stay put for decades, that’s a conversation worth having with a loan officer before you commit.

Want to see this with your own numbers? A Gershman Mortgage loan officer can run a side-by-side fixed vs. ARM comparison based on your actual loan amount and credit profile.

ARM vs. Fixed-Rate Mortgage: Which One Fits You?

An ARM tends to make the most sense if:

• You know you’ll move or refinance before the fixed period ends
• You want the lowest possible payment for the first several years
• You’re comfortable with some payment variability down the road

A fixed-rate loan might be the better fit if:

• You plan to stay in the home long-term
• You want the same payment every single month, no surprises
• Rate uncertainty stresses you out more than it’s worth

There’s no wrong answer here. It’s about matching the loan to your actual plans, not just chasing the lowest number on day one.

FAQ: Adjustable-Rate Mortgages

How does an adjustable-rate mortgage actually work? It starts with a fixed rate for a set number of years, then adjusts once a year based on market conditions. The annual and life-of-loan caps limit how much that adjustment can be, so it moves in controlled steps rather than jumping all at once.

Can my ARM payment go up every year forever? No. The annual cap limits how much it can move each year, and the life-of-loan cap sets a hard ceiling on the highest rate you’ll ever pay.

Can my rate go down too, not just up? Yes. ARMs adjust based on market conditions, so if rates drop, your rate can drop with them, within the same cap limits.

What happens after the fixed period ends? Your rate starts adjusting once a year, based on current market conditions and the terms of your specific loan.

Is a 5-year ARM the same as a 5/1 ARM? Yes, that’s the common way to say it. The first number is the number of years your rate stays fixed. The “1” means it adjusts annually after that.

Do all ARMs have the same caps? No. As you can see above, caps vary depending on whether you have a 1-, 3-, 5-, 7-, or 10-year ARM, and conventional loans set their own cap structures separately from FHA. Always ask your loan officer for the exact cap structure on your specific loan before you sign anything.

Should I choose an ARM just because the rate is lower? Not on its own. A lower starting rate is nice, but the right call depends on how long you’ll keep the loan and whether you’re okay with the rate changing later.

Talk to a Loan Officer Before You Decide

ARMs aren’t complicated once you know what the caps do. But every borrower’s situation is different, and the math only works out if the loan matches your plans.

If you’re weighing a fixed-rate loan against an ARM, reach out to a Gershman Mortgage loan officer. We’ll walk through your numbers together and help you figure out which option makes sense for you.

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At Gershman Mortgage, communities, families, and homes are at the heart of what we do. We’ve been doing this since 1955 – over 70 years of helping people finance homes across the Midwest and beyond. We’re independently owned, underwrite loans in-house and licensed in 22 states. Built on the core values of honesty, integrity, entrepreneurial spirit, and customer-first service, we’re committed to providing an exceptional homebuying experience. Our goal is simple: to exceed expectations and build lifelong relationships.

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Source: HUD.gov, Section 203 ARM Mortgages