A 5-year ARM on a mortgage means your interest rate is fixed for the first sixty months of the loan and then adjusts on a recurring schedule for the rest of the term. The starting rate typically runs about half a percentage point below a comparable 30-year fixed mortgage, which can translate into meaningful savings during those first five years. After the fixed window closes, your rate moves up or down with a market benchmark, subject to contractual caps that limit how far it can swing in any single adjustment and over the life of the loan.
The First Five Years Are Fixed
The “5” refers to sixty months during which your interest rate, and therefore your monthly principal and interest payment, does not change. In this stretch the loan behaves exactly like a traditional fixed-rate mortgage. The promissory note you sign at closing legally binds the lender to that rate for the full five years.
Federal rules require the lender to deliver a Loan Estimate within three business days of your application. For an ARM, that disclosure has to spell out the starting rate, how often the rate can adjust after the fixed period, the maximum rate the loan can ever reach, and projected payments at different stages of the loan.1eCFR. 12 CFR 1026.37 – Content of Disclosures for Certain Mortgage Transactions (Loan Estimate) Read those projected payments carefully, because they tell you the worst case you’ve agreed to.
What Happens After Year Five
Once the fixed window closes, your rate resets on a recurring schedule set by the loan’s name. A 5/1 ARM adjusts once every twelve months for the remaining twenty-five years. A 5/6 ARM resets every six months. That second number is written into your contract at closing and cannot be changed later.2Consumer Financial Protection Bureau. Consumer Handbook on Adjustable-Rate Mortgages
You will not be surprised by an adjustment. Federal law requires the lender to send advance notice before each rate change. For the very first adjustment, the notice must arrive at least 210 days (roughly seven months) before your new payment is due. For every adjustment after that, the notice must come at least 60 days ahead.3eCFR. 12 CFR 1026.20 – Disclosure Requirements Regarding Post-Consummation Events That first seven-month heads-up is generous on purpose. It gives you time to refinance, sell, or adjust your budget before the adjustable phase begins.
How the New Rate Is Calculated
Each adjusted rate comes from a simple formula: a market index plus a fixed margin.
The index on virtually all new ARMs today is the Secured Overnight Financing Rate (SOFR), which replaced LIBOR. Fannie Mae and Freddie Mac stopped buying LIBOR-based ARMs at the end of 2020,4FHFA. LIBOR Transition and HUD has adopted SOFR for FHA adjustable-rate loans.5Federal Register. Adjustable Rate Mortgages: Transitioning From LIBOR to Alternate Indices SOFR itself moves with broader interest rate conditions.
The margin is a fixed percentage the lender sets when you originate the loan. It never changes. Common margins fall somewhere around 2 to 3 percentage points. To find your new rate, the lender adds the current SOFR value to your margin. As of early March 2026, the 30-day average SOFR sat at roughly 3.67 percent.6FRED. 30-Day Average SOFR (SOFR30DAYAVG) With a 2.5 percent margin, the fully indexed rate at that snapshot would be about 6.17 percent. That number becomes your rate for the upcoming adjustment period, subject to the caps below.
Caps That Limit How Far Your Rate Can Move
Every ARM carries contractual caps that keep the rate from swinging without bounds. They usually appear as three numbers separated by slashes, such as 2/1/5.
- The initial adjustment cap limits how much your rate can jump at the very first reset. A cap of 2 means the rate can rise no more than 2 percentage points above your starting rate at that first adjustment.
- The periodic adjustment cap restricts movement at each later reset, most commonly 1 or 2 percentage points per adjustment.7Consumer Financial Protection Bureau. What Are Rate Caps With an Adjustable-Rate Mortgage (ARM), and How Do They Work?
- The lifetime cap sets an absolute ceiling the rate can never exceed. Most land at 5 percentage points above the initial rate, so a loan starting at 4 percent with a 5-point lifetime cap tops out at 9 percent.7Consumer Financial Protection Bureau. What Are Rate Caps With an Adjustable-Rate Mortgage (ARM), and How Do They Work?
The loan also has a floor, the minimum rate it can reach even if SOFR crashes. The floor is often equal to the margin itself.
Cap structures vary. You might see 2/1/5, 2/2/5, or 1/1/5 on some FHA and VA products. The differences matter more than they look. A 2/2/5 lets your rate climb 2 points per adjustment; a 2/1/5 caps subsequent moves at 1 point. Over several years of rising rates, that gap adds up to thousands of dollars.
What the Payment Jump Can Look Like
Even with caps, the shift from fixed to adjustable payments can be substantial. Take a $300,000 loan at 3.37 percent during the fixed period: monthly principal and interest runs about $1,060. If the initial adjustment cap is 2 percentage points and rates have risen enough to trigger the full cap, the rate climbs to 5.37 percent and the payment jumps to roughly $1,302, about $242 more each month.
That’s just the first adjustment. If rates keep rising and the periodic cap allows another point the following year, you’d be at 6.37 percent with a payment near $1,429. Two years in, the monthly obligation has grown by nearly $370 compared to the fixed-period payment. Federal rules require lenders to show the maximum possible payment on your Loan Estimate, calculated by assuming rates rise as fast as the caps allow.8Consumer Financial Protection Bureau. 12 CFR 1026.19 – Certain Mortgage and Variable-Rate Transactions
The flip side is real too. If market rates have fallen by the time your fixed period ends, your payment can drop. But planning around a best case is how borrowers get into trouble. Budget for the worst-case payment on your Loan Estimate and treat any savings as a bonus.
How Lenders Qualify You
Lenders do not qualify you based on the low introductory rate. For a 5-year ARM, Fannie Mae requires the lender to use the greater of two numbers: the note rate plus the initial adjustment cap, or the fully indexed rate (the current index plus your margin).9Fannie Mae. Qualifying Payment Requirements Your debt-to-income ratio is calculated as if you were already paying the higher adjusted rate.
The practical effect is that you’ll qualify for a smaller loan amount with an ARM than the teaser rate alone would suggest. This is a deliberate consumer protection. If a lender isn’t qualifying you this way, ask why.
Your Exits Before or After the Reset
Federal law effectively bans prepayment penalties on adjustable-rate mortgages for primary residences. Any residential mortgage that isn’t a “qualified mortgage” cannot carry a prepayment penalty, and the statute explicitly provides that a qualified mortgage cannot include an adjustable-rate loan for prepayment penalty purposes.10Office of the Law Revision Counsel. 15 USC 1639c – Minimum Standards for Residential Mortgage Transactions You can pay off or refinance your 5-year ARM at any point without owing a penalty.
That matters because the most common exit strategy is refinancing before the adjustable phase begins. Refinancing still carries closing costs, typically 1 to 2 percent of the loan balance, plus another full round of underwriting. Run the numbers before assuming it will pencil out.
Some ARM contracts also include a conversion clause that lets you switch to a fixed-rate loan without a full refinance. The new fixed rate is based on market rates at the time you convert, not your original ARM rate. Not every ARM has this option, and the window to use it may be limited. If an escape hatch matters to you, ask about conversion before you close.
When a 5-Year ARM Makes Sense
A 5-year ARM is not a one-size-fits-all product. It works best in a few specific situations.
- You plan to move within five to seven years. If you expect to sell before the first reset, you capture the lower rate without ever facing the adjustable phase. Military families, corporate transferees, and buyers of starter homes often fit here.
- You expect to refinance. If you believe rates will drop before your fixed period ends, an ARM lets you ride the lower introductory rate now and lock in fixed later. The risk is that rates don’t cooperate, or that your situation changes and you can’t qualify when the time comes.
- You plan to pay down principal aggressively. The monthly savings can be redirected to extra principal, reducing the balance exposed to future rate changes.
A 5-year ARM is a weaker fit if you’re buying your long-term home on a tight budget with no margin for payment increases. The introductory savings look attractive, but they come with a real possibility that your payment rises by several hundred dollars a month in year six. If that would strain your finances, a 30-year fixed costs more upfront and removes the uncertainty.
The honest version is this: a 5-year ARM rewards borrowers who have a clear exit plan and the financial flexibility to absorb the worst-case adjustment. If either piece is missing, the introductory savings aren’t worth the risk.