Amortization vs Interest-Only Loans: Key Differences for Commercial Real Estate
Compare amortizing loans vs interest-only loans and understand how each structure impacts your cash flow, DSCR, returns, and overall investment strategy.
Two loan structures, two very different cash flow profiles
Every commercial real estate loan has a payment structure that determines how much cash leaves your account each month. The two primary structures are fully amortizing loans (where each payment includes both principal and interest) and interest-only loans (where you pay only interest for a defined period, with no principal reduction).
The structure you choose — or that your lender offers — directly affects your monthly payment amount, DSCR, cash-on-cash return, equity buildup, and refinancing risk. Understanding the tradeoffs between these structures is essential for modeling any commercial property acquisition.
How each structure works
Principal + interest payments
Each monthly payment includes both interest on the outstanding balance and a portion of principal. Early payments are mostly interest; over time, the principal share grows as the balance declines.
The amortization period (typically 20, 25, or 30 years) determines the payment schedule. A longer amortization means lower monthly payments but slower principal paydown and more total interest paid.
By the end of the amortization period, the loan would be fully repaid. However, since most commercial loans have shorter terms (5–10 years), a balloon payment covers the remaining balance at maturity.
Interest-only payments
During the interest-only (I/O) period, you pay only the interest accruing on the loan balance — no principal reduction. Your payment is simply the loan balance multiplied by the annual interest rate, divided by 12.
I/O periods typically last 1 to 5 years, after which the loan converts to fully amortizing payments for the remaining term. Some bridge and construction loans are interest-only for their entire term.
Because you’re not paying down principal during the I/O period, the full loan balance remains outstanding. When the I/O period ends and the loan begins amortizing, the monthly payment increases — sometimes significantly.
Side-by-side comparison: same deal, different structure
Let's model the same $5,000,000 industrial acquisition with a $3,500,000 loan at 6.25% under both structures to see how the numbers change.
| Metric | Amortizing (25-yr) | Interest-Only (2-yr I/O) | Difference |
|---|---|---|---|
| Monthly Payment | $23,088 | $18,229 (I/O period) | $4,859 lower during I/O |
| Annual Debt Service | $277,061 | $218,750 (I/O period) | $58,311 lower during I/O |
| NOI (assumed) | $375,000 | $375,000 | Same |
| Annual Cash Flow | $97,939 | $156,250 (I/O period) | $58,311 more during I/O |
| DSCR | 1.35x | 1.71x (I/O period) | 0.36x higher during I/O |
| Cash-on-Cash | 6.53% | 10.42% (I/O period) | 3.89% higher during I/O |
| Equity Buildup (Yr 1) | ~$60,000 principal paid | $0 principal paid | No equity buildup during I/O |
| Balloon at Maturity (Yr 7) | ~$2,990,000 | ~$3,099,000 | $110K larger balloon after I/O |
The core tradeoff
Interest-only gives you higher cash flow, better DSCR, and higher cash-on-cash return in the short term — but you build zero equity and carry a larger balloon payment at maturity. Amortizing loans deliver lower current cash flow but steadily reduce your loan balance, building equity with every payment and reducing refinancing risk.
Lower Payment
Interest-Only Advantage
Equity Buildup
Amortizing Advantage
Balloon Payment Risk
Both Have
When to use each structure
When amortizing makes sense
Stabilized, long-hold acquisitions. If you’re buying a fully leased property and plan to hold it for 7+ years, amortizing payments build equity steadily. Each payment reduces your loan balance, which improves your LTV for future refinancing and increases net proceeds at sale. The lower current cash flow is offset by the wealth accumulation happening through principal paydown.
Conservative underwriting. Amortizing payments force discipline — you’re living within the property’s means and building a cushion against refinancing risk. If property values decline, you’ll still have paid down a meaningful chunk of the loan.
When interest-only makes sense
Value-add and transitional deals. If the property isn’t stabilized — vacant space to lease, below-market rents to roll, or renovations planned — I/O payments preserve cash flow during the execution period. You minimize carrying costs while spending capital on improvements that increase NOI. Once stabilized, the loan converts to amortizing (or you refinance into permanent debt).
Short hold periods. If you plan to sell within 2–3 years, principal paydown provides minimal benefit since you’ll pay off the loan at sale anyway. I/O maximizes your cash-on-cash return during the hold and lets you deploy saved capital elsewhere.
Bridge loans and construction financing. These transitional loan products are almost always structured as interest-only because the underlying property is in flux — being renovated, developed, or repositioned. Requiring amortization during a period of unstable income would create unnecessary cash flow pressure.
Hybrid structures
Many commercial real estate loans offer a hybrid: 1–3 years of interest-only followed by amortizing payments for the remaining term. This gives borrowers the cash flow benefit of I/O during the early stabilization period while transitioning to equity-building payments once the property is performing. The key is ensuring the property’s NOI can comfortably support the higher amortizing payment when the I/O period ends.
Impact on DSCR and financing
DSCR is directly affected by the loan structure because it compares NOI against annual debt service. Interest-only payments produce lower debt service, which inflates DSCR. This can be meaningful for marginal deals:
A property with $300,000 NOI and $250,000 annual amortizing debt service has a 1.20x DSCR — barely meeting the lender’s minimum. The same property with I/O debt service of $195,000 produces a 1.54x DSCR — comfortably above threshold.
However, most lenders are aware of this dynamic. Many underwrite DSCR based on the fully amortizing payment even during the I/O period to ensure the property can support the higher payment when it kicks in. If the amortizing DSCR doesn’t pass, the I/O period won’t save the deal — it just delays the problem.
Some lenders will offer a more favorable I/O structure if the property demonstrates a clear path to higher NOI during the I/O period (lease-up, rent bumps, expense reduction). In these cases, they’re underwriting to the stabilized DSCR with confidence that NOI will rise to support the amortizing payment.
How DealWise AI helps
DealWise AI lets you toggle between amortizing and interest-only structures and instantly see how each affects your monthly payment, DSCR, and annual cash flow. Model hybrid structures with I/O periods and see the payment transition in your cash flow projections.
Frequently asked questions
Do I pay less total interest with an amortizing loan?
Yes — over the full life of the loan. Because amortizing payments reduce the principal balance each month, you're paying interest on a declining balance. With interest-only, the balance stays flat, so you pay interest on the full amount for the entire I/O period. However, if you sell the property before the loan matures, the total interest difference may be less significant than the cash flow advantage of I/O during the hold.
Can I switch from interest-only to amortizing mid-loan?
Most I/O loans automatically convert to amortizing after the I/O period ends — this is built into the loan documents. Going the other direction (amortizing to I/O) would require a loan modification, which lenders rarely approve without a compelling reason. If you want I/O flexibility, negotiate it upfront at origination.
Which structure do lenders prefer?
It depends on the lender and the deal. Banks and credit unions generally prefer amortizing loans because they reduce credit exposure over time. CMBS and agency lenders may offer I/O periods as a standard feature on stabilized properties. Bridge lenders almost always structure as I/O because the loans are short-term by design. The borrower's track record, the property's performance, and the overall deal structure all influence what a lender will offer.
How does interest-only affect my balloon payment?
Interest-only increases your balloon payment because you haven't paid down any principal during the I/O period. If you borrow $3.5M and make 2 years of I/O payments, you still owe $3.5M. With amortizing payments, you might owe $3.3M after 2 years. The larger balloon creates more refinancing risk — you need higher property value or more equity to refinance.
Is interest-only riskier than amortizing?
Interest-only carries more refinancing risk and builds no equity, but it's not inherently riskier if used strategically. For a value-add deal where cash is needed for improvements, I/O preserves capital for productive use. For a stabilized long-hold deal where there's no value-add thesis, I/O just delays equity buildup without a strategic reason. The risk is in the mismatch between structure and strategy, not in the structure itself.
Final thoughts
Amortizing and interest-only aren’t inherently good or bad — they’re tools that serve different strategies. Amortizing builds equity and reduces risk over time. Interest-only maximizes current cash flow and preserves capital for active investment strategies. The right choice depends on your hold period, your business plan, and whether you need current income or future equity buildup.
DealWise AI lets you model both structures side by side so you can see exactly how each one impacts your deal’s returns before you commit to financing terms.
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Amortization vs interest-only: full comparison guide
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DealWise AI derives NOI from your actual rent roll, then runs amortizing and interest-only against it side by side — payment, DSCR and balloon, month by month. Free to start.