Adjustable-rate mortgages
An adjustable-rate mortgage is fixed for a set number of years and then adjusts on a schedule. It is a legitimate, well-regulated product, and right now it prices below a fixed rate. So let me put my answer first: I do not usually recommend one unless the pricing advantage is unusually strong, and preferably not on anything shorter than a seven-year fixed period. Here is how they work, how I think about them, and the cases where the math genuinely favors one.
What a 5/6, 7/6 or 10/6 actually is.
The first number is the years your rate is fixed. The second number is how often it adjusts afterwards, in months. A 7/6 is fixed for seven years, then adjusts every six months for the remaining twenty-three.
If you learned this as “5/1” and “7/1,” you learned the old product. Conforming ARMs moved to six-month resets when the industry left LIBOR behind. The naming still lags in places — the mortgage industry’s own weekly rate survey continues to label its series “5/1 ARM” for a product that has not existed in conforming form for years.
The three numbers that set your rate after the fixed period
- The index. Conforming ARMs are tied to the 30-day average of SOFR, published daily by the Federal Reserve Bank of New York. It moves with short-term funding markets. It is currently sitting in the neighborhood of 3.6%, and it is a live number — look it up, do not take mine.
- The margin. A fixed number added to the index, set at origination and never changing for the life of the loan. The agencies permit a margin between 100 and 300 basis points. It gets less attention than the initial rate and deserves more, because a 2.75% margin and a 2.25% margin are half a point apart for thirty years.
- The caps. How far the rate can move at the first adjustment, at each one after, and in total. Covered below, because they differ by plan in a way that matters.
Index plus margin is your fully indexed rate, rounded to the nearest one eighth of a percent — and rounded down when it lands exactly in the middle. At each adjustment the index value used is the one in effect 45 days before. That lookback is why you can see your next rate coming.
There is a floor, and it is the margin. Your rate can never fall below the margin, no matter how far the index drops. On a 2.75% margin, SOFR going to zero puts you at 2.75%, not lower. Worth knowing before you build a plan around rates collapsing.
The first adjustment is not capped the same way on every plan.
| Plan | Fixed for | First adjustment | Each one after | Lifetime |
|---|---|---|---|---|
| 3/6 SOFR | 3 years | 2% | 1% | 5% |
| 5/6 SOFR | 5 years | 2% | 1% | 5% |
| 7/6 SOFR | 7 years | 5% | 1% | 5% |
| 10/6 SOFR | 10 years | 5% | 1% | 5% |
On the 7/6 and 10/6, the first-adjustment cap equals the lifetime cap. There is nothing standing between your note rate and your maximum rate except one adjustment date. The 5/6 climbs a staircase — 2% at month 61, then 1% every six months, reaching its ceiling somewhere around month 96. The 10/6 can take the whole flight in one step at month 121.
What that looks like on a real payment
A $400,000 10/6 ARM at a note rate of 5.99%, thirty-year term.
Years one to ten
Principal and interest of about $2,396 a month. After ten years the balance is roughly $334,650.
Month 121, worst case under the cap
Rate goes to 10.99%. The remaining balance re-amortizes over twenty years at about $3,451 a month.
Up $1,056 a month — a 44% increase — on a single date. That is not a market catastrophe or a loophole. That is the contract performing as written. The question an ARM asks you is not “do you think rates will fall?” It is “can you write that check if they do not?”
To be fair to the product: this is the ceiling, not the forecast. The rate is capped in both directions, the floor is the margin, and there is a strong argument that a borrower with a genuinely short horizon should not pay a premium to insure against year eleven. But you should be shown the ceiling before you sign, not after, and it should be a number you have actually looked at.
Four things that decide whether an ARM is worth it.
1. Your interest cost is front-loaded, so the fixed period is where the money is
This is the part of the argument that actually favors an ARM, and it has nothing to do with predicting rates. On any amortizing mortgage you pay the most interest at the beginning, because that is when the balance is highest. It is true at every price point and every rate.
A $400,000 loan at 6.69%, thirty-year fixed
Your first payment
$2,578, of which $2,230 is interest — about 86%. By year twenty, interest is down to roughly 49% of the same payment.
Where the interest actually falls
Over thirty years you would pay about $528,000 in interest. Roughly 47% of it lands in the first ten years.
So a rate saving during the fixed period is worth considerably more than the same saving later. On that loan, 72 basis points saves about $14,500 over five years and $20,200 over seven — and that is before counting the extra principal a lower rate pays down. This is the real case for an ARM, and it does not require rates to cooperate.
2. The pricing advantage is not the same for every borrower
Headline ARM rates get quoted as though everyone gets them. On a real rate sheet, the spreads on adjustable products are tight, and the loan-level adjustments stack differently than they do on a fixed rate. The practical effect is that the ARM discount is largest for the strongest files — high credit score, low loan-to-value — and it narrows as the profile softens.
A 740 score at 80% loan-to-value, for example, will often find the ARM pricing barely better than the fixed once the adjustments are applied. Nothing is wrong with that borrower, and nothing is wrong with that file. It just means the trade being offered — take on adjustment risk to save money — may not be paying enough to be worth taking.
Which is why this is a pricing question before it is a strategy question. The right order is: price both on your actual credit and loan-to-value, see what the gap really is, and only then decide whether the gap justifies the risk. If the ARM is only a quarter point better on your file, there is not much left to talk about.
3. They make more sense when rates are high — as a goal, not a guarantee
When fixed rates are elevated, an ARM buys you a lower payment now with the intention of refinancing later. That is a reasonable plan, and it is worth being precise about the word: refinancing is the goal, not the guarantee. Nobody can promise you the market will be there.
The protection, if the plan does not work out, is the cap structure and the absence of a prepayment penalty. The exposure is that you are still holding the loan on a date you did not choose. Both of those are real, and the honest version of this argument holds both at once.
4. Seven years, as a preference
Given all of the above, a seven-year fixed period is the shortest I am generally comfortable recommending, and ten is better. A five-year ARM also carries the tighter qualifying test, so it is the harder file and the shorter runway.
None of this makes an ARM wrong. It makes it a product with a narrow set of borrowers it genuinely suits, and I would rather tell you where that line is than let you find it at the first adjustment.
The loans that blew up are not the loans you would be offered.
Plenty of people have the same reaction to the word “adjustable,” and it is a reasonable one. Here is the precise answer rather than the reassuring one.
What actually caused the damage was not the adjustment itself. It was three features that were routinely bolted onto adjustable loans: qualifying borrowers at a teaser rate they were never going to pay, negative amortization that let the balance grow, and interest-only or option-payment structures that deferred principal indefinitely. Combine those and the reset was not an adjustment; it was a cliff.
| The 2006 feature | Where it stands today |
|---|---|
| Qualifying at the teaser rate | Prohibited — must underwrite to the fully indexed rate or the introductory rate, whichever is greater |
| Negative amortization | Cannot be a Qualified Mortgage |
| Interest-only | Cannot be a Qualified Mortgage |
| Balloon payment | Cannot be a Qualified Mortgage, outside a narrow small-creditor exception |
| Option ARM / pick-a-payment | Fails on all of the above; not agency-eligible |
| Prepayment penalty on an ARM | Not permitted on a Qualified Mortgage — penalties are limited to fixed-rate QMs |
I am going to be pedantic about one word, because it matters. You will read that option ARMs are “illegal.” They are not banned outright by statute. The accurate statement is that a negative-amortization or interest-only loan cannot be a Qualified Mortgage, cannot be qualified at a teaser rate, and is not eligible for sale to Fannie Mae or Freddie Mac. That is a stronger claim than “illegal,” because it is true and it survives scrutiny. Anyone who tells you “illegal” has handed a competitor an easy rebuttal.
The practical upshot for you: the prepayment rule means an ARM cannot trap you. If rates fall and you want out, there is no penalty on the way. That answers the most common objection I hear, which is some version of “what if I need to get out of it?”
A 7/6 is easier to qualify for than a 5/6.
Because the rules require underwriting to a stress-tested rate rather than the note rate, the length of your fixed period changes how hard the file is to approve — and not in the direction most people guess.
| Initial fixed period | You are qualified at |
|---|---|
| Three years or less | The maximum rate possible in the first five years |
| Five years | The greater of note rate plus the first-adjustment cap, or the fully indexed rate |
| More than five years | No less than the note rate |
So a 5/6 at 5.99% is underwritten at roughly 7.99% or the fully indexed rate, whichever is higher — while a 7/6 at a similar rate is generally underwritten at the note rate itself. On a tight debt-to-income file that difference decides the approval. The exception is a higher-priced loan, where the fully indexed rate applies regardless and the file may have to be underwritten manually.
There is a regulatory reason underneath this, and it explains pricing behavior that otherwise looks arbitrary. A loan whose rate can change within the first five years has to be tested for compliance using the maximum rate that could apply during those five years as though it were the rate for the whole term. A 7/6 or 10/6 cannot change inside five years, so that test does not catch it. The shorter ARM is structurally harder to fit inside the rules, and the pricing reflects it.
Government ARMs run on a different index, with different caps.
This is a genuinely under-covered corner, partly because HUD’s own consumer-facing page still lists LIBOR as an index option years after that transition finished.
FHA
Indexed to the one-year Constant Maturity Treasury or the 30-day average SOFR, adjusting annually. The caps split by term: one- and three-year FHA ARMs move 1 point per adjustment with a 5-point lifetime cap; five-, seven- and ten-year FHA ARMs move 2 points per adjustment with a 6-point lifetime cap. Excess index movement cannot be carried forward into a later adjustment.
VA
VA has not moved to SOFR. Only CMT-indexed products are eligible for guaranty. Adjustments are annual, and the first one cannot occur sooner than 36 months after your first payment. The caps are notably tighter than conventional: no single adjustment may change the rate by more than one percentage point, in either direction, and no more than five points over the life of the loan. Rate changes can only be implemented through the monthly payment — VA does not permit extending the term instead.
VA also layers on its own disclosure: a written explanation with a hypothetical payment schedule showing the maximum increases, and a written certification from you that you understand it.
Two corrections worth flagging
You will see it stated widely that VA hybrid ARMs carry 2%/6% caps. As the regulation reads today, the 1-point and 5-point limits apply uniformly, with no separate tier for longer fixed periods. VA proposed adding a 2/6 tier in mid-2024, and I have not found a final rule adopting it. Treat 1/5 as current and confirm before relying on it either way.
And a live-market note: the one-year CMT was 4.09% on 28 July 2026, while 30-day average SOFR is running near 3.6%. Government ARMs are currently repricing off an index roughly half a point above the conventional one. That gap moves, and it will not always run this direction — but it is worth checking rather than assuming the two track together.
You get seven months of warning before the first adjustment.
- At application — or before you pay a non-refundable fee, whichever comes first — you must receive the Consumer Handbook on Adjustable-Rate Mortgages, plus a program disclosure for each variable-rate program you have expressed interest in, covering the index, the margin, adjustment frequency, the rate and payment limits, and a historical or maximum-rate example.
- Before the first adjustment, your servicer must send a notice at least 210 and no more than 240 days before the first payment at the new level is due. That is seven to eight months of advance notice, and it must include your alternatives — refinancing, sale, modification, forbearance — and homeownership counselling resources.
- Before every later adjustment, a notice at least 60 and no more than 120 days ahead. A 5/6 adjusts every six months, which is not frequent enough to trigger the shortened 25-day rule some explainers apply to it by mistake.
Use the 210-day notice as a calendar entry, not a piece of mail. Seven months is enough time to refinance, sell, or restructure comfortably. The people who get hurt by ARMs are not the ones who got surprised — the notice makes surprise nearly impossible. They are the ones who read it, planned to refinance, and found the rate had moved against them. Put the date in your calendar at closing, not when the letter arrives.
Sometimes the ARM is not a choice you make. It is how the loan is built.
Building a house. On a single-close construction-to-permanent loan, the only amortization change permitted at conversion is from adjustable to fixed. That runs one direction only, and it is a real planning tool: carry an adjustable structure through the build, convert to fixed at completion. If you are building, how construction-to-permanent financing works covers where this sits in the sequence.
Texas home equity. A Texas Section 50(a)(6) loan can only be a fixed rate or one of the five-, seven- or ten-year ARM plans. The three-year plan is not eligible, and the loan cannot be assumable at any point in its term. The Texas cash-out rules cover the rest of that picture.
I will write you an ARM. I will not sell you one.
For a specific kind of borrower an ARM is the right answer, and the math in the section above is why. It is also the product where the gap between a good recommendation and a bad one is widest, because a bad one feels fine for five to ten years before it does not.
So the conversation is short, and it is about you rather than the rate sheet. Is there a specific, identifiable reason your horizon in this house is shorter than the fixed period — a residency ending, a relocation clause, a house you already know you will outgrow? Does the file still work at the fully indexed rate, not just the note rate? And if the adjustment arrives and you are still there, can you carry note-plus-five?
Three yeses, a pricing gap worth having, and a seven- or ten-year fixed period, and an ARM is a good decision. Short of that I will say so, and you can weigh it from there.
That last point deserves its own page, because the standard industry argument for ARMs rests on a number that stopped being true about a decade ago. The honest ARM versus fixed comparison is where I work through it.
Questions I get asked about ARMs.
Can my rate double?
No. Your rate is capped at the note rate plus 5 percentage points for the life of the loan on a conforming ARM, and lower on FHA and VA products. From a 6% note rate the absolute ceiling is 11%. Your payment can rise by considerably more than the rate does, though, because the remaining balance re-amortizes over a shorter term.
Is there a prepayment penalty?
Not on a Qualified Mortgage. Prepayment penalties are limited to fixed-rate qualified mortgages, so an ARM that is a QM cannot carry one. You can refinance or sell whenever you want without a charge for leaving.
What happens if I still own the house at the first adjustment?
Your rate resets to the index plus your margin, subject to the caps, and your payment is recalculated over the remaining term. You will have received notice 210 to 240 days beforehand. Nothing is called due and nothing balloons.
Can I convert my ARM to a fixed rate later?
Not by conversion. The standard conforming SOFR ARM plans are non-convertible, so switching to a fixed rate means refinancing into a new loan at whatever rates are then available. The one exception is a single-close construction loan, where converting from adjustable to fixed at completion is built into the structure.
Can I get an ARM on a rental property or a second home?
Yes. Both agencies permit adjustable-rate mortgages on principal residences, second homes and investment properties, and on purchases, rate-and-term refinances and cash-out refinances. The maximum loan-to-value varies by occupancy and purpose.
How is the margin set, and can I negotiate it?
The margin is set by the lender or investor within a permitted range of 100 to 300 basis points, and it is fixed for the life of the loan. It is not usually negotiable directly, but it does differ between lenders, so it is worth comparing the margin and not only the initial rate when you shop.
Let’s find out whether you are actually the right borrower for one.
Tell me how long you expect to be in the house and why. I will price the ARM and the fixed side by side, show you the worst case under the caps, and tell you plainly which one I would take in your position.
Talk First
Text or email the situation — price, down payment, and honestly how long you think you will be there. I will respond within one business day. No pressure and no rate-sheet pitch.
Or Get Real Numbers
Send the full scenario and I will come back with ARM and fixed pricing side by side, including the margin, the caps and the worst-case payment — wholesale, not marked up.
Send my scenario →Cap structures, index requirements and qualifying rules are drawn from agency selling guide requirements, 24 CFR 203.49, 38 CFR 36.4312 and 12 CFR 1026.20, 1026.19 and 1026.43, current as of July 2026. Index values cited were current on the dates given and change daily. The payment illustration assumes a $400,000 loan, a 5.99% note rate, a 30-year term and the maximum permitted adjustment; it is a ceiling, not a forecast, and your actual terms depend on credit, property, occupancy, program and investor. Forest Hills Mortgage · Matt Mergo · NMLS #563819. Equal Housing Opportunity.