DSCR sizing with actual and underwritten debt service

A property can cover its current payment comfortably and still support a smaller loan under the lender’s underwriting payment. The difference often lies in the denominator: interest-only payments, amortizing payments, a stressed rate, and a covenant-defined payment are different measures. Before comparing coverage ratios, identify which debt service each ratio uses.

A program-specific illustration appears in Fannie Mae’s Small Mortgage Loan DSCR table, which uses level amortizing debt service and the greater of note rate or its applicable underwriting floor. Official indexed text was inspected; direct retrieval was restricted. This guide does not state the current floor, a universal minimum DSCR, or eligibility for that program. Its original comparison uses fictional terms.

Give each denominator a name and date

Create four rows: contractual payment now, contractual payment after any scheduled change, proposed underwriting payment, and the loan’s actual covenant payment definition. Add rate basis, amortization, payment frequency, principal balance, effective date, and included charges. A covenant definition may differ from the initial sizing method, so preserve both.

For a floating loan, distinguish today’s index from the rate used to stress repayment. A purchased interest-rate cap may generate separate receipts; it does not necessarily rewrite the note payment. If fees, reserve deposits, subordinate payments, or hedge receipts enter a test, identify the relevant definition rather than quietly adding or subtracting them.

Keep the numerator equally controlled. A property cash-flow figure before replacement allowances cannot be compared directly with a different lender’s net cash flow without a bridge. This article holds the numerator constant to isolate the payment effect.

Work a three-payment comparison

Assume $500,000 of annual recognized cash flow and a $4 million proposed balance. The fictional loan initially requires interest-only payments at 6%, giving $240,000 of annual debt service. A separate hypothetical underwriting case uses 7.5%, monthly payments, and 30-year amortization. All payments occur at month-end; fees and reserves are excluded.

The monthly amortizing payment is principal multiplied by the monthly rate, divided by one minus the present-value factor for 360 payments. Its annual debt service is approximately $335,623. A third scenario assumes 6% interest but 25-year amortization, producing approximately $309,265 annually.

The rates and structures are assumptions, not a quote. The table shows why saying “DSCR is over two” without identifying the payment can mislead an acquisition team.

Reverse the correct payment into principal

At an illustrative minimum DSCR of 1.25, the $500,000 numerator permits $400,000 of annual debt service. Using a 6% interest-only denominator yields a cash-flow limit of about $6.667 million. Using the 7.5%/30-year amortizing denominator yields approximately $4.767 million.

That roughly $1.899 million difference is not an arbitrary reduction by a lender. It follows from using a different assumed payment for each borrowed dollar. Other value, cost, size, or sponsor constraints may still reduce the final loan below either result.

For a spreadsheet cross-check, Microsoft’s PMT documentation specifies consistent periodic rates and payment counts. Under the stated month-end assumptions, -PMT(7.5%/12,360,4000000)*12 produces annual principal and interest. Do not enter 30 as the payment count while dividing the rate by twelve.

Reconcile an interest-only period that ends midyear

A borrower cash budget may need a mixed year. If the first six payments are interest-only and the next six amortize, calculate the actual sequence from the contract. Do not choose whichever annualized payment makes coverage look best. A lender’s sizing test may still use a full year of amortizing debt service even though the first operating year contains only part of that burden.

The mixed-year schedule also needs a principal roll-forward. Payments after amortization begins reduce the balance, while interest-only payments generally leave it unchanged under the stated no-curtailment assumption. A future payment calculated on an unchanged opening balance is an approximation unless the contract specifies it.

At maturity, the remaining principal is a separate repayment event. A ratio based on periodic debt service does not establish that the borrower can pay a balloon. Prepare an exit analysis using the future balance and the next financing assumptions.

Resolve disagreements at the definition level

When a lender’s number differs from the borrower’s model, request its recognized cash flow, tested principal, rate, amortization, payment frequency, and treatment of reserves or other debt. Reproduce the result before attributing the difference to credit appetite. A small discrepancy may reflect rounding; a large one may reflect an entirely different denominator.

The final comparison should preserve the actual payment for budgeting and the underwritten payment for sizing, with the contractual covenant separately identified. That lets an investor understand both near-term cash burden and the lender’s repayment test without presenting one favorable ratio as the answer to every financing question.