Fixed vs Adjustable-Rate Mortgages: Understanding Your Options

Somewhere in the process of figuring out your mortgage, and it might not be until you're pre-approved, you're going to have to decide between a fixed-rate and an adjustable-rate loan. It's easy to let that decision be made for you, but it's a big one, both for your monthly budget and for your wallet five or ten years from now. A few minutes of research here can save you thousands.

Fixed: know what you're getting into

With a fixed-rate loan, your interest rate, and your payment on principal and interest along with it, is locked in for the life of the loan, typically 15 or 30 years.

It's the safe option. The rate never increases, so you always know what to expect from your payments. That is a huge benefit for long-term budgeting, since you know today what the payment will be in 2031 and beyond. There's also no fine print to be surprised by, because there are no rate adjustments of any kind. The only real downside is that you'll pay a somewhat higher initial rate than an adjustable loan offers, and if rates drop significantly in the future, you have to go through the trouble of refinancing to capture the benefit. Nothing earth-shattering. The 30-year fixed is America's favorite mortgage for a reason.

Adjustable: the rate changes as time goes on

With an adjustable-rate mortgage (ARM), your interest rate changes over the life of the loan. ARMs almost always have a fixed period at the beginning, after which the rate adjusts on a schedule tied to a market index, and they're named for that structure. A 5/1 ARM is fixed for five years, then adjusts every year after.

The benefit is the starting price. Because the initial rate is lower, often by half a point to a full point, your payments are lower during the fixed period. That makes an ARM attractive if you're confident you'll sell or refinance before the fixed period ends. The downside is that once adjustments start, your payment can rise substantially, on a schedule you don't control. For the average buyer settling into a primary residence, ARMs carry more fine print and more ways to be surprised.

Side by side

	30-year fixed	5/1 ARM
Starting rate	Higher	Lower (often by 0.5-1%)
Payment predictability	Locked for 30 years	Locked for 5, then changes yearly
Risk if rates rise	None	Payment could rise substantially
Benefit if rates fall	Only by refinancing	Rate could fall on its own
Complexity	Straightforward	Caps, indexes, margins
Best if	You're staying long-term, or want zero rate risk	You expect to sell within the fixed period and want the lower rate meanwhile

To put the rates in perspective, a 0.75-point difference on a $350,000 loan is roughly $170 a month, which is a nice amount to have around during the fixed years. But if that ARM later adjusts up by two points, the payment jumps by more than $400 a month, and that's a number you don't control. Run your own figures in the mortgage calculator, and see how much of each payment goes to interest with the amortization calculator. If you consider an ARM, ask the lender about the caps, which limit how much the rate can rise at each adjustment and over the loan's lifetime. Then ask what your payment would be at the lifetime cap. If that number is shocking, you have your answer.

Deciding between the two

The decision comes down to two things: how long you expect to keep the loan, and how much risk you're willing to accept. A fixed-rate mortgage fits most people who plan to stay put, and everyone who wants to skip rate risk entirely. An ARM only makes sense if you genuinely expect to sell or refinance before the adjustments begin, understand the caps, and could survive the worst-case payment anyway.

One warning: don't use an ARM's lower initial rate as an excuse to buy a more expensive house than you could afford at the fixed rate. If the house only works at the teaser rate, it doesn't work. Before rate shopping at all, it's worth establishing how much house you can actually afford.

On a brighter note, no mortgage is permanent. If rates fall after you take a fixed loan, you can refinance to the lower rate, though closing costs apply. That flexibility is why many people take the predictable fixed rate now and treat refinancing as their option on future rate drops, rather than taking on an ARM's uncertainty from day one.

Most of the time, the predictability of a fixed-rate mortgage is worth the slightly higher rate. Knowing what you're getting into is the whole game, so understand both options, and whichever you pick, pick it informed.

---

This article is for general educational purposes only and does not constitute personal financial, investment, tax, or legal advice. Consult a qualified financial professional before making major financial decisions. See our Disclaimer.