What Is an Adjustable-Rate Mortgage (ARM), and Is It Risky?
An ARM has a fixed rate for a set period, commonly 3, 5 or 7 years, then adjusts on a schedule based on a market index. It carries more payment uncertainty than a fixed-rate loan, but today's rules make it a different product from the ones blamed for 2008: rate caps limit how far it can move, and lenders have to qualify you at a higher rate than the introductory one.
Last updated September 29, 2026How does the rate change after the fixed period?
During the fixed period, it doesn't move. After that, it resets on the schedule in your loan terms, at a market index plus a margin the lender sets. Adjustments aren't always yearly; some ARMs, including many tied to SOFR, adjust every six months, so check the schedule before you sign.
What limits how far it can rise?
Lenders have to disclose the caps, and there are usually three:
- Initial cap: limits the first adjustment, commonly 2 or 5 percentage points.
- Periodic cap: limits each later adjustment, commonly 1 or 2 points.
- Lifetime cap: limits the total increase over the loan's life, commonly about 5 points.
The caps stop the rate from rising without limit, but budget for the highest payment the loan allows, not just today's.
Is an ARM riskier than a fixed-rate loan?
Its payment can change after the fixed period, while a fixed rate's never does, so there's more built-in uncertainty. But underwriting changed after 2008. Under the federal ability-to-repay rules, lenders generally have to qualify you using the highest rate the loan could reach in its first five years, not a low introductory rate. And a qualified mortgage can't include negative amortization, interest-only payments or balloon payments. Caps were already standard before 2008; the bigger change was in underwriting and in which loan features are allowed.
It depends on your situation:
- You expect to sell, refinance or move within the fixed period: the lower starting rate may save money before it ever adjusts.
- You'll stay well past the fixed period and want certainty: a fixed rate usually fits better.
- Your budget can't absorb a higher payment: weigh the caps carefully, or lean toward a fixed rate.
| Initial fixed period | Commonly 3, 5 or 7 years |
|---|---|
| Initial cap | Commonly 2 or 5 points |
| Periodic cap | Commonly 1 or 2 points |
| Lifetime cap | Commonly about 5 points |
| How you're qualified | At the highest rate possible in the first five years, under federal rules |
Related questions
Sources
- https://files.consumerfinance.gov/f/documents/cfpb_charm_booklet.pdf
- https://www.consumerfinance.gov/ask-cfpb/what-are-rate-caps-with-an-adjustable-rate-mortgage-arm-and-how-do-they-work-en-1951
- https://www.consumerfinance.gov/ask-cfpb/if-i-am-considering-an-adjustable-rate-mortgage-arm-what-should-i-look-out-for-in-the-fine-print-en-1947
- https://files.consumerfinance.gov/f/documents/cfpb_ability-to-repay-qualified-mortgage_assessment-report.pdf
Sourced from licensed loan officers and brokers in the FreeRateUpdate network.
Educational information only, not individualized financial or legal advice. Program details and rates change; verify current terms with a licensed loan officer before making a decision.