What Is an Adjustable-Rate Mortgage? How ARM Loans Work

If you’re exploring mortgage options, you’ve likely come across the term adjustable-rate mortgage – also called an ARM loan or ARM mortgage. But what exactly is an adjustable-rate mortgage, and how does it work? Whether you’re browsing homes for sale in Denver, CO or planning to make an offer on a home in Miami, FL, knowing how an ARM works can help you choose the best financing option for your needs.

This Redfin guide explains what an adjustable-rate mortgage is, how it works, the different types available, their pros and cons, and who they might be right for.

What is an adjustable-rate mortgage?

An adjustable-rate mortgage (ARM) is a type of home loan where the interest rate can change over time. Unlike a fixed-rate mortgage, which keeps the same rate for the entire term, an ARM mortgage typically starts with a lower introductory interest rate that adjusts periodically based on market conditions.

How an adjustable-rate mortgage works

ARM loans have two phases:

1. Initial fixed-rate period: This is usually 3, 5, 7, or 10 years, during which the interest rate is fixed and typically lower than a fixed-rate mortgage.
2. Adjustment period: After the fixed period ends, the interest rate can adjust annually (or sometimes more frequently), based on an index (like the SOFR or Treasury index) plus a fixed margin set by the lender.

ARM loan vs. fixed-rate mortgage

Types of adjustable-rate mortgages

ARM loans come in different structures, often identified by two numbers (like 5/1 or 7/6) that describe the fixed period and how often the rate adjusts afterward. Understanding the types of ARMs can help you choose the right one for your financial goals. Common ARM Types:

• 3/1 ARM: Fixed interest rate for the first 3 years, then adjusts once per year.
• 5/1 ARM: Fixed rate for 5 years, then adjusts annually. One of the most popular options.
• 7/1 ARM: Fixed rate for 7 years, then adjusts yearly. Often chosen by buyers who plan to stay longer before selling or refinancing.
• 10/1 ARM: Fixed rate for 10 years, then adjusts annually. Offers the longest fixed period but typically a slightly higher initial rate than shorter ARMs.
• 5/6 ARM or 7/6 ARM: Fixed rate for the initial term (5 or 7 years), then adjusts every 6 months instead of once a year.

Tip: When comparing ARM types, pay close attention to the index, margin, and rate caps – these factors determine how much and how often your rate can change after the fixed period.

Key features of ARM loans

How to qualify for an adjustable-rate mortgage

Qualifying for an adjustable-rate mortgage is similar to qualifying for a fixed-rate loan, but lenders may have specific requirements to ensure you can handle potential rate increases. Common requirements include: 

• Credit score: Many lenders prefer a score of at least 620–640, though higher scores can help secure a lower introductory rate.
• Debt-to-income (DTI) ratio: Typically 43% or lower, showing you can manage monthly payments even if rates rise.
• Stable income: Lenders will review pay stubs, W-2s, or tax returns to confirm consistent earnings.
• Down payment: Minimum down payments vary but are often 5%–10% for conventional ARMs.
• Sufficient reserves: Some lenders require cash reserves to cover a certain number of months’ mortgage payments.

Tip: Because ARM rates can increase, lenders may use a “qualifying rate” (higher than your initial rate) to ensure you can still afford payments after adjustments.

Refinancing an adjustable-rate mortgage

Refinancing an adjustable-rate mortgage can be a smart move, especially before your fixed-rate period ends or if interest rates have dropped. By refinancing, you can switch to a fixed-rate mortgage for predictable payments or even refinance into a new ARM if market conditions are favorable. When to consider refinancing:

• Before the first adjustment: Locking in a fixed rate before your ARM resets can protect you from potential payment increases.
• When rates are lower: Refinancing during a low-rate environment can help you save money over the life of the loan.
• If your finances have changed: Improved credit, higher income, or lower debt may qualify you for a better rate and terms.

>> Read: Should I Refinance My Mortgage?

Pros and cons of an adjustable-rate mortgage

Pros:

• Lower initial payments: Great for short-term homeowners or those expecting income increases.
• Potential for lower long-term rates: If interest rates fall, your rate (and payment) could decrease.
• Affordability: Lower upfront costs can help buyers qualify for a more expensive home.

Cons:

• Rate uncertainty: Payments can increase significantly after the fixed period.
• Refinancing risk: You may need to refinance if rates rise too high.
• Complexity: ARM terms, indexes, and caps can be confusing.

Who should consider an ARM loan?

An adjustable-rate mortgage may be a good fit if you:

• You plan to sell or refinance before the initial fixed-rate period ends.
• You expect your income to increase in the coming years.
• You want a lower initial monthly payment to improve cash flow in the short term.

>> Read: How to Get the Best Mortgage Rate

FAQs about adjustable-rate mortgages

1. Do ARM loans always go up?

Not necessarily. ARM interest rates are tied to a market index and can go up or down depending on economic conditions. However, many borrowers see increases when the adjustment period begins – especially if rates have risen since the loan originated.

2. Can you refinance an ARM loan?

Yes. Many homeowners refinance into a fixed-rate mortgage before the adjustment period begins to lock in a more stable rate.

3. What is a rate cap?

Rate caps limit how much your interest rate can increase during an adjustment. There are typically three types:

• Initial cap: limit on the first adjustment
• Periodic cap: limit on subsequent adjustments
• Lifetime cap: maximum your rate can ever increase over the life of the loan

Final thoughts: Is an adjustable-rate mortgage right for you?

ARM loans offer lower initial rates, which can be a smart financial move for certain buyers—especially those with shorter-term homeownership plans or expectations of falling rates. However, they come with the risk of rising payments, so it’s important to carefully evaluate your financial stability, market trends, and long-term plans.

Always compare your options and speak with a mortgage lender to find the right fit for your situation.

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