The ARM Is Saving Buyers $284 a Month Right Now. The Government's Own Example Shows the Year-8 Bill.

Update, October 7, 2026: Rates jumped since we first ran these numbers. In the MBA survey for the week ending October 2, the 30-year fixed hit 7.49%, its highest in almost three years, while the 5/1 ARM slipped to 6.43%. The gap widened from 85 to 106 basis points, and the monthly difference on $400,000 grew from $222 to about $284. The math below is updated. The CFPB’s year-8 warning hasn’t changed.

If you are shopping a mortgage this month, the adjustable is the cheap one, and it is not close. The average contract rate on a 5/1 ARM was 6.43% in the week ending October 2. The 30-year fixed was 7.49%. That is 106 basis points of daylight, and roughly one applicant in ten is now taking it.

On a $400,000 loan over 30 years, the fixed costs about $2,794 a month in principal and interest. The ARM costs about $2,510. Call it $284 a month, roughly $17,000 across the five years before anything adjusts.

That is real money, not a rounding error, and the market has noticed. ARM share held at 10.3% of applications, up from 8.0% in late August. The MBA’s Joel Kan said “a higher share of borrowers are opting for ARMs to lower their initial payments,” and that very few homeowners have any reason to refinance at these rates.

So take the discount? Slow down.

Here’s the catch

The CFPB publishes a sample 5/1 ARM in its own handbook, and it is the most useful document nobody reads. The loan is $216,000 at a 3% start rate. First adjustment capped at 2%. Each adjustment after that capped at 2%. Lifetime maximum 8%.

Principal and interest: $910.66 a month in years one through five.

By year eight, as high as $1,467.

That is a 61% jump, and it is not a scare number. It is the maximum the contract allows, printed by the government on a sample form. The CFPB’s guidance sits right next to it: “Consider an ARM only if you can afford increases in your monthly payment, even to the maximum amount.”

The other line worth memorizing is the tip: do not count on refinancing your way out before the rate resets. You might not qualify if your home’s value drops or you lose a job. Plenty of people made that plan in 2006 and discovered the refinance window closes exactly when you need it.

Do this now

Ask each lender for a Loan Estimate on the ARM, then turn to page 2 and read four lines in the Adjustable Interest Rate table. Index plus margin. Initial rate. Minimum and maximum rate. Limits on rate changes, first and subsequent. Those four lines are the entire deal.

Then flip to page 1 and find Projected Payments. It prints the maximum payment for each stretch of the loan in dollars. Ask yourself the only question that matters: on today’s income, could you write that check?

If yes, the 106 basis points are yours to take. If the honest answer is “we would have to refinance,” take the fixed and stop negotiating with yourself.

Run both payments through our mortgage calculator with your real numbers, and shop the fixed quote just as hard. The spread is wide today, and a fixed quote 25 basis points under the average narrows the gap fast. Our mortgages hub and best mortgage picks cover where to look.

Verdict: your call, genuinely. Worth taking if you are confident you are gone inside five years or you can carry the maximum. Dumb math if your plan depends on a refinance that has to show up on schedule.

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