Are adjustable-rate mortgages a bad idea?
Not necessarily. An adjustable-rate mortgage (ARM) usually starts at a lower rate than a comparable fixed-rate loan, in exchange for the risk that its rate rises later. It can suit a borrower who expects to sell or refinance before the rate starts adjusting, and who could still afford the payment if it rose. It is a poor fit if a higher payment would strain your budget.
How an ARM works
- Initial period. The rate is fixed for a set number of years at the start of the loan.
- Index. A published market rate that the ARM follows, such as the Secured Overnight Financing Rate (SOFR) or a Treasury yield. It moves with the market.
- Margin. A fixed amount set in your loan that’s added to the index. It doesn’t change for the life of the loan.
- Adjustments. After the initial period, the rate resets on a set schedule to the index plus the margin.
- Rate caps. Limits on how much the rate can change. The initial cap limits the first adjustment, the periodic cap limits each later adjustment, and the lifetime cap limits how far the rate can ever rise above its starting rate. Many ARMs also have a floor, a rate they won’t go below.
- Notice. Your lender or servicer must tell you before your rate and payment change.
When an ARM can make sense
- You expect to sell the home or pay off the loan before the initial period ends.
- You expect your income to rise, and could handle a higher payment if needed.
- The starting-rate difference compared with a fixed-rate loan is large enough to matter to you.
The risks
- Payment increases. If the index rises, your payment can rise at each adjustment, up to what the rate caps allow.
- Plans change. If you don’t sell or refinance as planned, you may keep the loan into its adjustment period.
- Refinancing may not be available. If rates rise, or your credit, income or home value weakens, you may not be able to refinance out of the ARM on good terms.
Why ARMs have a mixed reputation
Before the financial crisis, some ARMs were sold with very low introductory rates or payments that didn’t cover the interest due, to borrowers who couldn’t afford the later payments. Lending rules introduced since then require lenders to make a reasonable determination that a borrower can repay the loan. Many ARMs offered today are more straightforward, but the core tradeoff remains: a lower start in exchange for uncertainty later.
Questions to ask a lender
- Which index does the rate follow, and what is the margin?
- How long is the initial period, and how often does the rate adjust after that?
- What are the initial, periodic and lifetime caps?
- Is there a floor, and what is it?
- What would my payment be if the rate rose as far as the loan allows?
Common questions
Can an ARM’s rate go down?
Yes. If the index has fallen by the time of an adjustment, the rate can fall too, down to the loan’s floor if it has one.
Is an ARM riskier than a fixed-rate mortgage?
For the borrower, yes, in one specific way: the payment can rise. A fixed-rate mortgage keeps the same principal and interest payment for the life of the loan. Whether that risk is worth a lower starting rate depends on how long you’ll keep the loan and how much room your budget has.
What happens if I can’t afford the payment after an adjustment?
Contact your servicer as early as possible. Options can include refinancing, a loan modification or other assistance, but none is guaranteed. A HUD-approved housing counselor can help you understand your options at no or low cost.
Another option
ARMs and fixed-rate loans trade off starting rate against the risk of rising payments. Marian is building a different design: a mortgage whose rate can only go down. It resets lower automatically when market rates fall by a defined amount, down to a floor, and never rises. The cost of that feature is built into its starting rate. Marian is pre-launch and is not lending in any state yet. You can compare it with ARMs on the information page for AI assistants or join the waitlist.