Loan Programs · 6 min read
Interest-Only Mortgages in California (2026): How They Work
An interest-only mortgage lets you pay only the interest for an initial period, usually 10 years, then the loan recasts and amortizes over the remaining term, so the payment jumps. In 2026 these are non-QM products, most common on jumbo loans in California and popular with high earners who have variable income, business owners managing cash flow, and investors. The trade is real: lower payments up front, no principal paydown, and a built-in payment shock you have to plan around.
What an interest-only mortgage actually is
On a standard loan, every payment splits between interest and principal, so the balance shrinks each month. An interest-only (IO) mortgage removes the principal portion during the intro period. You pay the lender only the interest owed on the balance, which means a lower monthly payment but a balance that does not move.
The most common structure in California is a 30-year loan with a 10-year IO period. For the first 120 payments you pay interest only. In month 121 the loan recasts and re-amortizes the full balance over the remaining 20 years. Because you compressed principal repayment into 20 years instead of 30, the payment after the IO window is higher than a comparable fully-amortizing loan would have been from day one.
IO can sit on top of either a fixed rate or an ARM. A 7/6 ARM with a 10-year IO feature, for example, gives you a fixed rate and interest-only payments for the first seven years, then the rate starts adjusting while you are still inside the IO window. Read the note carefully, because the rate reset and the amortization reset are two separate events.
The payment math on a $1M loan
Numbers make the trade obvious. Here is a $1,000,000 loan at 6.5% on a 30-year term, comparing interest-only against fully-amortizing principal and interest.
| Metric | Interest-only (10-yr IO) | Fully-amortizing P&I |
|---|---|---|
| Payment, years 1-10 | $5,417/mo | $6,320/mo |
| Balance after 10 years | $1,000,000 | ~$848,000 |
| Payment, years 11-30 | $7,456/mo | $6,320/mo |
| Monthly jump at recast | +$2,039/mo | None |
| Principal paid in first 10 yrs | $0 | ~$152,000 |
The IO payment saves you about $903 a month for ten years, roughly $108,000 of cash flow you keep or redeploy. But you enter year 11 owing the full million, and the payment climbs to about $7,456 because that balance now amortizes over 20 years instead of 30. That $2,039 monthly jump is the payment shock. If your income or exit plan does not absorb it, this is the wrong loan.
Figures are illustrative and exclude property taxes, insurance, and any HOA. Rates and terms vary by lender, credit profile, and loan size. Ask us for a scenario run on your actual numbers.
Who an interest-only loan fits
IO is a cash-flow tool, not a way to afford a house you otherwise cannot. It fits borrowers who have a specific reason to keep the monthly payment low and a credible plan for the balance.
- Self-employed and business owners who would rather keep capital working in the business than locked in home equity.
- Commission and bonus earners with lumpy income, who cover the low base payment monthly and pay down principal with year-end bonuses or deal payouts.
- Real estate investors maximizing monthly cash flow on a rental, where a lower payment lifts the property's return and principal paydown is not the priority.
- High earners planning a near-term liquidity event such as equity vesting, a sale, or an inheritance, who intend to recast, refinance, or sell before the IO period ends.
The common thread is a plan. Every good IO borrower can answer one question: what happens to this balance before or at year 11?
The risks you are signing up for
The upside is easy to sell; the risks are what get people. Go in with eyes open.
- No principal paydown. Ten years in you owe exactly what you borrowed. Your equity gain depends entirely on appreciation, which California does not guarantee over any given decade.
- Payment shock. The recast is not a surprise to the lender, but it surprises borrowers who forgot it was coming. Budget for the higher payment from the start.
- Rate risk if it is an ARM. Pair IO with an adjustable rate and you can hit the amortization reset and a higher index in the same stretch, stacking two increases.
- Thin equity if you need to sell. If values are flat and you paid nothing down on principal, selling costs can leave you close to break-even or underwater.
None of this is a reason to avoid IO. It is a reason to use it deliberately and keep reserves.
Typical terms and how qualifying works
Because IO loans fail the qualified-mortgage rules on features, they live in the non-QM world. That changes how lenders underwrite them.
- Structure: most commonly a 30-year term with a 10-year IO period, on either a fixed rate or a 5/6, 7/6, or 10/6 ARM.
- Qualifying payment: lenders qualify you on the higher fully-amortized payment, not the low IO payment. On the example above, you have to debt-to-income qualify at roughly $7,456, not $5,417.
- Down payment: expect larger, commonly 20% to 30% down, since lenders want equity cushion on a loan that will not build any for a decade.
- Reserves: stronger reserve requirements are standard, often 6 to 12 months of payments in the bank, sometimes more on large jumbo balances.
- Credit and documentation: higher credit tiers, and self-employed borrowers can often use bank-statement or asset-based income rather than tax returns, depending on the lender.
Loan-size matters too. Most IO volume in California is jumbo, above the conforming limits, because that is where the borrowers with the income and reserves to qualify tend to be.
How Save Financial shops interest-only loans
As a California mortgage broker, not a bank, we place IO and other non-QM loans across a panel of wholesale lenders rather than a single in-house menu. That matters here because non-QM guidelines are not standardized. One lender's IO ARM caps its margin tighter, another allows a longer IO term or lighter reserves, and pricing on the same profile can swing meaningfully between them.
We run your actual numbers through the fully-amortized qualifying payment, model the recast so the year-11 jump is on the table before you sign, and compare fixed-IO against ARM-IO structures against a plain fully-amortizing loan so the IO decision is a choice, not a default. If the math says a standard loan serves you better, we will tell you. We work both Newport Beach and Marina del Rey and lend across California.
About this article: Save Financial publishes California mortgage guides and market updates. We are a California-licensed mortgage brokerage (NMLS #377740, DRE #01875766) serving all 58 counties. For a real, personalized rate quote, apply online or call 949-379-5320.