What Is Interest-Only Loan?
With an interest-only loan, your monthly payment covers only interest. The principal balance doesn't decrease. That means lower payments than a fully amortizing loan—but you're not building equity through paydown. Common in commercial loans (5–10 year terms, IO for the full period, then balloon), construction loans (IO during build), and bridge financing. For investors, IO improves cash flow in the short term. The trade-off: you must refinance or sell before the balloon payment. If the property doesn't support a refi (low appraisal, high rates), you're stuck. Negative leverage is easier to tolerate with IO—you're not adding principal paydown to the cost—but you're also not building equity from amortization.
An interest-only loan is financing where the borrower pays only interest for a set period—no principal reduction. The principal balance stays flat. At the end of the period, a balloon payment is typically due, or the loan converts to amortizing payments.
At a Glance
- What it is: Loan where you pay only interest; no principal reduction
- Payment: Lower than amortizing—interest only
- Principal: Stays flat during IO period
- Exit: Balloon payment or conversion at end of period
- Common in: Commercial loans, construction, bridge
How It Works
The payment math
$500,000 loan at 7% interest-only. Monthly payment: $500,000 × 0.07 ÷ 12 = $2,917. That's it. No principal. The balance stays $500,000. Compare to a 30-year amortizing loan at 7%: payment would be ~$3,327. The extra $410 goes to principal. With IO, you save $410/month—but you've built zero equity from paydown. Your equity comes only from appreciation (or value-add).
Why lenders offer IO
Commercial loans are typically 5–10 year terms with balloon payments. Lenders don't expect the loan to amortize—they expect a refi or sale. IO keeps payments low and matches the short-term nature. Construction loans use IO during the build because there's no income yet—why pay principal when you're not earning rent?
Cash flow benefit
For investors, IO maximizes cash flow in the early years. A $1 million commercial loan at 6.5% IO: payment = $5,417/month. Amortizing over 25 years: ~$6,750/month. The $1,333 difference stays in your pocket. Useful when you're value-adding or when the property's yield is thin. The trade-off: no equity build from paydown. You're betting on appreciation or refi to extract value.
Balloon and refinance
At the end of the IO period, the full principal balance is due—the balloon payment. You refinance or sell. If you can't, you're in default. IO loans are bridge financing—plan your exit before you sign.
Real-World Example
Vikram buys a 24-unit in Charlotte for $1.8 million. He gets a commercial loan: $1.35 million (75% LTV), 6.25% interest-only for 5 years. Payment: $7,031/month. NOI: $108,000/year ($9,000/month). Debt service: $84,372/year. Debt coverage ratio: 1.28x. Cash flow: ~$2,000/month.
If the loan were amortizing over 25 years, his payment would be ~$8,900. Cash flow would drop to ~$100/month. The IO structure gives him breathing room. At year 5, he must refinance the $1.35 million balloon. He's added value—raised rents, reduced expenses. New NOI: $135,000. Property value: $2.25 million. He refis at 75% LTV: $1.69 million. Pays off the $1.35 million, nets $340,000 for the next deal. The IO period gave him time to stabilize and add value.
Pros & Cons
- Lower payments than amortizing—maximizes cash flow
- Common in commercial loans—industry standard
- Useful for value-add and bridge—time to stabilize before refi
- Construction loans use IO during build (no rent yet)
- No equity build from principal paydown
- Balloon payment requires refi or sale
- Refi risk—rates or property performance can block exit
- Negative leverage doesn't improve with paydown
Watch Out
Balloon timing: The balloon payment is the full principal balance. Start refinance discussions 12–18 months before the balloon. Don't wait until the last month.
Rate environment: If rates rise, your refi may be at a higher rate. Model the worst case. Can you afford amortizing payments at 8%? If not, the IO was a short-term fix that could become a long-term problem.
Residential IO: IO mortgages exist for 1–4 unit residential but are less common than pre-2008. Often have adjustable-rate and balloon. Higher risk for homeowners. For investors, commercial loans are the typical IO source.
Cash flow vs equity: IO prioritizes cash flow. If you're holding long-term and want equity build, an amortizing loan may be better. Match the loan structure to your strategy.
The Takeaway
Interest-only loans lower payments and improve cash flow by deferring principal. Common in commercial loans and construction. The trade-off: no equity from paydown, and you must refinance or sell before the balloon payment. Use IO when you have a clear exit and the property will support a refi. Don't use it as a permanent solution without a plan.