How Are ARM Interest Rates Calculated After the Initial Period?
After the fixed period ends, the rate resets based on an index — commonly the Secured Overnight Financing Rate (SOFR) — plus a set margin. Rate caps limit how much the rate can rise at each adjustment and over the loan's lifetime. Common caps are 2/2/5, meaning no more than 2% increase at first adjustment, 2% per subsequent adjustment, and 5% total over the loan.
Who Should Consider an Adjustable-Rate Mortgage?
ARMs make sense for borrowers who expect to sell or refinance before the fixed period ends. They're also suitable for buyers confident rates will fall, or those who need a lower starting payment to qualify. Military families and people with predictable relocation timelines often favor ARMs. The key risk is holding the loan into the adjustable phase if rates have risen.
What Are the Risks of an Adjustable-Rate Mortgage?
Payment shock is the primary risk — your monthly payment can jump significantly when the rate adjusts. If your financial situation changes or you can't refinance before the adjustment, you could struggle. The 2008 housing crisis was partly driven by borrowers who couldn't afford their payments after ARM resets. Many experts recommend stress-testing a budget at the maximum capped rate before choosing an ARM.
Frequently asked questions
What does 5/1 ARM mean?
A 5/1 ARM has a fixed rate for the first five years, then adjusts once per year thereafter. The first number is the fixed period in years; the second is how often it adjusts after that.
Can an ARM rate go down as well as up?
Yes. If the underlying index falls, your ARM rate and payment can decrease. Caps apply in both directions on some loans. However, most borrowers focus on upside risk since rates can rise substantially over a 30-year term.