The honest answer is that it depends entirely on which payment your lender puts in the denominator, and the two conventions produce opposite outcomes. Freddie Mac's Optigo Conventional Fixed-Rate term sheet holds the minimum coverage ratio at 1.25x whether the loan amortizes or pays full-term interest-only — but a footnote on that same table specifies that the ratio during any interest-only period is calculated using an amortizing payment. Interest-only therefore buys no coverage credit at the agencies; it costs leverage instead, with maximum LTV falling from 75–80% down to 65–70%. Lenders that underwrite to the actual interest-only payment face the reverse problem — that payment is roughly a third smaller, so the ratio it produces is flattered — and they respond by setting a higher stated minimum. Both conventions are asking the same question: can this property carry the debt once principal comes due?
How is DSCR calculated on an interest-only loan?
Debt service coverage ratio divides net operating income by annual debt service, and on an interest-only loan the denominator has two possible definitions. Lenders either use the actual interest-only payment or a hypothetical fully amortizing payment. Which convention they choose changes the resulting ratio dramatically on identical property cash flow.
The textbook definition assumes principal is in the denominator. Per Corporate Finance Institute's DSCR guide, total debt service comprises the loan principal due within the measurement period plus aggregate interest due in that same period, and the guide notes most commercial banks want to see a minimum of 1.25x. An interest-only loan breaks that assumption, because for the duration of the IO period the principal component is genuinely zero.
That leaves underwriters with a choice. They can measure what the borrower pays today, or what the borrower must pay once the loan starts amortizing. The first is a cash-flow test. The second is a solvency test. Most institutional lenders care far more about the second, which is why the mechanics of how DSCR is calculated on a commercial property loan matter more than the headline threshold.
The distinction in one line: an interest-only DSCR tells you whether the property covers its coupon; an amortizing DSCR tells you whether it covers its debt.
Amortizing payment vs interest-only payment in the denominator
The gap between the two conventions is not a rounding difference, because the actual interest-only payment can run roughly 38% below the amortizing payment a lender underwrites. Fannie Mae's DSCR guidance job aid works a $10 million example where that spread moves a cooperative's actual-basis coverage from 1.00x to 1.43x.
Fannie Mae's DSCR Guidance job aid (information effective October 2017) is unusually explicit. For fixed-rate loans, it directs that underwritten annualized debt service be based on a level debt service payment with an amortization term, using the higher of the gross note rate or the required Underwriting Interest Rate Floor — and it applies that instruction to full and partial interest-only loans alike. Fannie Mae's current Multifamily Selling and Servicing Guide carries the identical rule forward, requiring the same level debt service payment, including amortization, regardless of the length of the interest-only period. The job aid then runs that instruction across three scenarios on the same $10,000,000 loan at a 4.00% note rate, a 5.00% underwriting floor and 360-month amortization.
| Loan structure | Underwritten NCF | Denominator applied | Annualized debt service | Resulting DSCR |
|---|---|---|---|---|
| Conventional, fully amortizing (0 months IO) | $1,000,000 | Amortizing at 5.00% floor | $644,186 | 1.55x |
| Conventional, partial IO (60 of 120 months) | $1,000,000 | Amortizing at 5.00% floor | $644,186 | 1.55x |
| Conventional, full-term IO (120 of 120 months) | $1,000,000 | Amortizing at 5.00% floor | $644,186 | 1.55x |
| Cooperative actual basis, 0 or 60 months IO | $573,000 | Amortizing at 4.00% note | $572,898 | 1.00x |
| Cooperative actual basis, full-term IO | $573,000 | Interest-only at 4.00% note | $400,000 | 1.43x |
The first three rows are the point. Fannie Mae reports the identical 1.55x for a fully amortizing loan, a five-year partial-IO loan and a full-term IO loan, because the denominator never changes. The last two rows are the counterexample, drawn from the job aid's cooperative sub-example rather than the conventional one — Fannie Mae permits an interest-only payment on that actual-property basis only for a full-term interest-only loan. The consequence is stark: the same $573,000 of cash flow covers the $572,898 amortizing payment 1.00x, and covers the $400,000 interest-only payment 1.43x. Nothing about the property improved.
What this means for sizing: if your lender uses the amortizing denominator, an interest-only period adds exactly zero dollars of loan proceeds. Building the amortizing payment yourself with an amortization schedule before you submit is the fastest way to know which number your lender will actually see.
Do lenders raise the minimum DSCR for interest-only?
Agency lenders generally hold the stated minimum coverage ratio flat and tighten leverage instead, while many non-agency lenders raise the required number itself. Freddie Mac keeps its minimum amortizing coverage ratio at 1.25x across both payment types but cuts maximum LTV by ten to fifteen points for full-term interest-only loans.
The Freddie Mac Optigo Conventional Fixed-Rate term sheet, dated 4/26, lays this out in a single table headed "LTV Ratios and Amortizing DCR."
| Loan term | Amortizing / partial IO: min amortizing DCR | Amortizing / partial IO: max LTV | Full-term IO: min amortizing DCR | Full-term IO: max LTV |
|---|---|---|---|---|
| 5-year and under 7-year | 1.25x | 75% | 1.25x | 65% |
| 7-year | 1.25x | 80% | 1.25x | 65% |
| Over 7-year | 1.25x | 80% | 1.25x | 70% |
Read across any row and the coverage requirement is unchanged. Read down the LTV columns and the cost of full-term interest-only becomes obvious: ten points of leverage on a five-year or over-seven-year deal, fifteen points on a seven-year. Freddie Mac's footnote removes any remaining ambiguity, stating that the DCR calculated for the partial-term and full-term interest-only period uses an amortizing payment.
Two further details in that term sheet matter. Partial-term interest-only loans must retain a minimum two-year amortization period, and any mortgage with under two years of amortization is pushed into the full-term interest-only bucket — so a ten-year loan with nine years of IO is priced and sized as full-term IO, not as a partial. Separately, Freddie Mac waives its Refinance Test entirely where the amortizing DCR is 1.40x or greater and LTV is 60% or less. That 1.40x is not a minimum to clear; it is the level at which the agency stops asking whether the loan can be refinanced at maturity.
The practical read: at the agencies, interest-only is bought with equity, not with coverage. Where a stated floor does move, it usually lands near the 1.25x minimum common to DSCR lending plus a spread for the missing amortization.
How agency and non-agency lenders treat IO differently
Non-agency lenders are far more likely to underwrite the payment the borrower actually makes, which mechanically inflates the ratio and forces a compensating adjustment. Debt funds, bridge lenders and business-purpose rental programs commonly quote interest-only minimums well above the amortizing equivalent, because they are measuring a smaller denominator against the same net operating income.
The logic is arithmetic, not philosophy. Take the two payments Fannie Mae publishes on the same $10,000,000 loan at its 4.00% note rate — $400,000 a year interest-only and $572,898 a year amortizing — and the interest-only denominator is about 30% smaller. Run our own arithmetic across those two published figures and a 1.25x threshold measured on the interest-only payment converts to roughly 0.87x once principal is added back, which is not a loan the property can service. Raising the stated interest-only minimum is how that lender restores the same real cushion the agencies get by changing the denominator instead.
This produces three broad patterns worth recognising on a term sheet:
- Amortizing-denominator lenders state one minimum, apply it to every payment type, and reduce proceeds through LTV. Fannie Mae and Freddie Mac sit here.
- IO-denominator lenders state a higher minimum for interest-only than for amortizing loans, often a quarter-turn or more above it, and may size to the lower of the two tests.
- Dual-test lenders publish both, requiring a floor on the actual payment and a lower shadow floor on a hypothetical amortizing payment. Bank balance-sheet lenders frequently work this way.
How to compare quotes correctly: never compare a 1.25x from one lender against a 1.40x from another until you have confirmed which payment each is dividing by. A lower stated threshold on an amortizing denominator is usually the stricter test.
When interest-only helps — and when it hurts — qualification
Interest-only helps most where the constraint is current cash flow rather than loan sizing, and hurts most where the borrower is reaching for maximum leverage. Because agency coverage tests ignore the IO structure entirely, borrowers pushing proceeds gain nothing and surrender ten to fifteen points of LTV for the privilege.
It genuinely helps in three situations. Value-add plans needing free cash flow during lease-up or renovation benefit, because the coupon-only payment preserves working capital while NOI is depressed. Deals already sized well inside the coverage test — say a 1.60x amortizing ratio against a 1.25x floor — can take IO without any proceeds penalty at all, since LTV is not the binding constraint. And investors managing distributions across a portfolio may accept lower leverage in exchange for predictable near-term cash.
It hurts in three others. A borrower at maximum LTV loses proceeds outright. A borrower who plans to hold past the IO period faces a payment shock at conversion, when principal enters the payment and the effective coverage drops toward the amortizing figure the lender underwrote all along. And a full-term IO loan repays no principal whatsoever, so the entire original balance comes due at maturity — a real consideration given MBA's February 10, 2026 finding that 17% of outstanding commercial and multifamily balances, some $875 billion of $5.0 trillion, mature in 2026, with multifamily maturities at 13% of that property type's balances.
The trap to avoid: treating a 1.43x interest-only ratio as evidence the deal is conservatively levered. That is the exact ratio Fannie Mae's cooperative sub-example produces, and recomputing it against the amortizing payment on the same $573,000 of cash flow leaves a bare 1.00x.
What today's rates mean for interest-only coverage tests
Higher underwriting rates compress amortizing coverage faster than they compress interest-only coverage, which widens the gap between the two conventions precisely when borrowers are most tempted to close it. Current benchmarks keep that gap live, and lenders have responded by competing on price rather than on leverage.
The Federal Reserve's H.15 Selected Interest Rates release dated August 31, 2026 put the 10-year Treasury constant maturity at 4.67% on August 27, 2026 and 4.73% on August 28, with the rate ranging from 4.64% to 4.73% that week, the federal funds effective rate at 3.63% and the bank prime loan rate at 6.75%. A 4.67% ten-year is materially above the 4.00% note rate in Fannie Mae's illustrative example, and every basis point of index widens the arithmetic distance between a coupon-only payment and a thirty-year amortizing one.
Underwriting has tightened alongside it. CBRE reported on August 3, 2026 that its Lending Momentum Index stood at 1.0 at the end of Q2 2026, easing from a five-year high of 1.5 in Q1 2026 and 1.3 a year earlier. Multifamily loan spreads tightened 15 basis points year over year to 162 bps while multifamily LTV ratios eased to 63.3% from 65.8%, and the debt service coverage ratio on originated loans rose to 1.43 from 1.34, with debt yield improving to 10.2% from 9.7%.
That combination is the story for interest-only borrowers. Spreads coming in while LTV comes down is lenders competing on price rather than leverage — exactly the environment in which a full-term IO request, which already costs ten to fifteen points of LTV at Freddie Mac, has the least room to run. A 63.3% average multifamily LTV sits close enough to Freddie Mac's 65% full-term IO ceiling that many borrowers already operate inside the constraint without having asked for interest-only.
If you are weighing an interest-only structure against an amortizing one, the decision turns on which lenders will size your file on which denominator — and that is faster to discover than to guess. Run the deal through YieldStack's lender match to see 5–8 lender matches drawn from 5,000+ loan programs, with $0 upfront and a median first offer in under an hour.
The bottom line
Do interest-only DSCR loans require a higher coverage ratio? At the agencies, no — Freddie Mac holds the minimum at 1.25x for both amortizing and full-term interest-only loans, and Fannie Mae returns the identical DSCR whether a loan has zero, sixty or one hundred twenty months of IO. Both simply compute the ratio on an amortizing payment, so interest-only never flatters the number. The price is paid in leverage: full-term IO drops maximum LTV to 65–70% from 75–80%.
Away from the agencies, the answer flips to yes, for a reason that is purely mechanical. A lender dividing by the actual interest-only payment is dividing by roughly a third less, so it must demand a higher ratio to preserve the same cushion. The threshold and the denominator are a matched pair, and quoting either one without the other is meaningless.
Ask any lender two questions before you compare term sheets: which payment goes in the denominator, and at what rate. Everything else about interest-only coverage follows from those answers.