What Is a 5/1 Adjustable Rate Mortgage

A 5/1 adjustable rate mortgage holds its interest rate fixed for the first five years, then resets once a year for the rest of the term to an index plus a lender's margin, within limits set by caps. On September 30, 2026, The Mortgage Reports put the conventional 5/1 ARM at 6.291%, against 7.343% for a 30-year fixed loan.

That gap matters to buyers choosing a loan this autumn. The lower rate buys five years of smaller payments. The cost is exposure to whatever the market charges after that, and the terms that govern that exposure are fixed at closing. Knowing how the reset works is how a borrower judges whether the discount is worth it.

For the first 60 months the note rate does not move. From year six, the lender recalculates it once a year using a formula the Consumer Financial Protection Bureau states as index plus margin, subject to caps.

The index is a market rate that neither borrower nor lender controls. On most current ARMs it is the Secured Overnight Financing Rate, or SOFR, which replaced LIBOR in US mortgage lending by mid-2023, according to Freddie Mac. Freddie Mac's conforming ARMs use the 30-day compounded average of SOFR published by the Federal Reserve Bank of New York. The CFPB says the lender selects the index at application, and it typically stays with the loan for life.

The margin is the lender's fixed markup. It is written into the loan agreement and does not change. Freddie Mac requires it to fall between 1% and 3% on the ARMs it buys, and its SOFR ARMs fact sheet cites 2.75% as the most common. The Mortgage Reports offers a worked example: SOFR at 2.0% plus a 2.25% margin produces a 4.25% rate, which the CFPB calls the fully indexed rate.

Caps limit how far that result can travel. Under a 2/2/5 structure, which The Mortgage Reports describes as common, the rate can rise up to 2 percentage points at the first adjustment, 2 points at each later one and 5 points over the life of the loan. A 2/1/5 structure, also in use, holds the annual step to 1 point. Freddie Mac adds a floor: the rate cannot fall below the margin, however low the index goes.

The size of the first-five-year saving depends on which survey is read, and on which day. Bankrate's national averages for September 30 were 6.89% APR for the 5/1 ARM and 7.42% APR for the 30-year fixed, a gap of about half a point. The Mortgage Reports' note-rate figures for the same date showed a gap of about a full point.

The Mortgage Bankers Association's survey for the week ending September 18 put the 5/1 ARM at 6.10% and the 30-year fixed at 7.12%, the fixed rate's highest since May 2024, according to Mortgage News Daily. On September 25, Yahoo Finance reported 6.88% against 7.21%, a gap of roughly a third of a point.

Surveys also differ in how many points they assume a borrower pays. That is one reason an individual quote against these averages needs reading line by line, not headline to headline.

The discount has shifted behavior. ARMs rose to 9.8% of mortgage applications in the week ending September 18, from 8.4% the week before, CNBC reported. During the pandemic-era low in fixed rates, the share was about 3%.

The 5/1 label survives on rate pages and in lender marketing, but Freddie Mac's conforming SOFR ARMs are structured as 5/6 loans: the same five-year fixed period, followed by adjustments every six months rather than once a year. Mortgage News Daily's "5/1" rate page now tracks a 7/6 product. A borrower quoted a "5/1" should confirm how often the rate actually resets.

Bankrate describes the 5/1 ARM as best suited to borrowers who plan to move or refinance within five years. For them, the adjustable period may never arrive, and the fixed years deliver a lower payment than a 30-year fixed loan at the same moment.

The case against is plain for anyone who expects to stay. An illustration in a September analysis on GetOutOfDebt.org shows a $400,000 balance resetting from 5.5% to 7.5% adds about $500 to the monthly payment over a 25-year remaining term. Refinancing out before the reset assumes rates will be lower in year five, which no survey can promise, and Bankrate notes that post-introductory rates track economic conditions and Federal Reserve policy moves.

The worst case can be computed before signing. On the 6.291% rate reported September 30, a 2/2/5 structure would permit 8.291% at the first reset and 11.291% at the lifetime ceiling. Whether five years of savings outweigh that exposure is a break-even calculation against a fixed loan.

Because the CFPB says margins vary significantly between lenders and can be negotiated, the same loan can reset to different rates depending on where it was taken out. These are the questions that separate one offer from another.