The DSCR formula
DSCR (Debt Service Coverage Ratio) measures whether the property earns enough to cover its own mortgage. A DSCR of 1.25 means the property earns $1.25 of NOI for every $1.00 of debt service — a 25% safety margin. DSCR loans (the non-QM product class) qualify your loan based on this ratio instead of your personal income.
Read the full background on the loan product itself: DSCR loans explained.
The 4-step process
Step 1: Compute NOI
Net operating income = gross rent − vacancy − operating expenses (taxes, insurance, management, maintenance reserve, CapEx reserve, utilities you pay, HOA). NOT including mortgage. Full walkthrough in how to calculate cap rate.
Step 2: Compute annual debt service
Monthly principal + interest payment × 12. Some DSCR lenders use PITIA (principal + interest + taxes + insurance + association dues) instead — check before locking. This matters because PITIA is meaningfully larger than P&I and pushes DSCR lower.
Step 3: Divide
NOI ÷ annual debt service = DSCR. Express to 2 decimals.
Step 4: Compare to lender minimum
Confirm the specific program's current formula, minimum, rent evidence, leverage, pricing, reserves, and other eligibility rules in writing. A modeled DSCR does not guarantee approval or a particular rate tier.
Worked example #1: comfortable DSCR
$200K property, 25% down at 7.5% (DSCR loan).
- Gross rent: $1,900/mo × 12 = $22,800
- Operating expenses (~45% ratio for Tier 2): −$10,260
- NOI: $12,540
- Loan: $150K at 7.5% / 30 yr = $1,049/mo P&I
- Annual debt service (P&I only): $12,588
- DSCR (P&I basis): $12,540 ÷ $12,588 = 1.00
Right at 1.0 — comfortable for a sub-1.0 product, marginal for a standard 1.25 program. Most investors target 1.25+ to avoid being a borderline case if the appraised rent comes in below your number.
Worked example #2: the PITIA version
Same property, but now the lender uses PITIA. Property tax $3,000, insurance $1,200 (both already in operating expenses but the lender double-dips here for safety).
- NOI: $12,540 (same as above)
- P&I: $12,588
- Tax + insurance escrow: $4,200
- Annual PITIA: $16,788
- DSCR (PITIA basis): $12,540 ÷ $16,788 = 0.75
Same property, but the PITIA-basis DSCR is 0.75 — well below any DSCR program's minimum. This is why it's critical to ask the lender which methodology they use before running your numbers. P&I basis is more common; PITIA basis is stricter and used by some banks and credit unions.
Worked example #3: strong DSCR
$200K property in higher-cap market, $2,200/mo rent, 25% down at 7.5%.
- Gross rent: $26,400
- Operating expenses (~45%): −$11,880
- NOI: $14,520
- P&I: $12,588 (same loan)
- DSCR: $14,520 ÷ $12,588 = 1.15
1.15 clears a 1.0-minimum program comfortably and qualifies for sub-1.25-tier pricing. If you can push rent another $150/mo or shave 10% off operating expenses, you cross 1.25 and unlock the better rate tier — often worth 25-50 basis points on the rate over 30 years.
Your DSCR vs the lender's DSCR
Your spreadsheet may differ from the lender's result because the inputs and formula can differ. Common questions include:
- Appraisal or program rent < your rent. Some programs use an appraisal rent form or other specified evidence. Ask which lease or appraisal rent the program accepts and test any supported downside.
- PITIA vs P&I. If you computed on P&I and the lender uses PITIA, recompute with the exact taxes, insurance, and association dues.
- Lender-imposed vacancy / management add-back.Ask whether and how the program applies vacancy, management, or other adjustments.
Ask the lender exactly which methodology and evidence it uses, then reproduce that calculation separately from your operating model. Choose a downside cushion based on the property and written program rather than a universal target.
Stress-test your DSCR
Before applying, run three scenarios:
- Base case with your rent and rate.
- Supported rent is lower — test a meaningful downside based on the available evidence.
- Rate or costs increase — test the written quote's expiration and a realistic pre-lock downside.
If all three pencil, the scenario has more modeled cushion; it still does not establish approval. If only the base case works, you have little modeled margin for surprises that happen on every other closing.
Related reading: DSCR loans explained, Hard money vs DSCR, Cap rate vs cash-on-cash vs DSCR.
FAQ
What's the DSCR formula?
DSCR = annual NOI ÷ annual debt service. NOI = net operating income (gross rent minus operating expenses, before debt service). Annual debt service = monthly mortgage payment × 12 (principal + interest only, sometimes including taxes and insurance depending on the lender). A DSCR of 1.25 means the property earns $1.25 for every $1 of mortgage payment — 25% margin of safety.
What DSCR do most lenders require?
There is no universal minimum or pricing tier. Ask the specific lender for its current written formula, rent evidence, expense treatment, threshold, leverage, pricing, reserve, borrower, property, and state requirements. A ratio below 1.0 under a given formula indicates modeled income is below modeled debt service; it does not by itself describe every cash-flow line or every lender decision.
How is the lender's DSCR calculation different from mine?
Lenders can differ on rent evidence, lease treatment, appraisal forms, PITIA versus other debt-service definitions, vacancy or management adjustments, and rounding. Obtain the exact written calculation before comparing it with your operating DSCR; the lender result can be higher or lower depending on the inputs.
What's a 1.25 DSCR loan in plain English?
Mathematically, 1.25 means the numerator is 1.25 times the denominator under the formula being used. In a hypothetical NOI-based calculation, $30,000 of NOI divided by $24,000 of debt service equals 1.25. Approval, pricing, and leverage still depend on the lender's formula and full program requirements.
Can DSCR be negative?
Mathematically yes if the numerator is negative. Re-check the income, vacancy, and operating-expense inputs and treat the result as a serious coverage warning. Do not infer a universal credit decision; ask the lender about its formula and program requirements.
What happens if my DSCR is right at the lender's minimum?
You're at risk. Lenders typically have a small cushion — they'll fund 1.05 if their minimum is 1.0 — but appraised rent coming in 5% below your number can tip you below. Don't lock a rate or pay non-refundable fees until you've confirmed the appraised rent in the 1007 form. If you're underwriting to a 1.25 minimum, target 1.4+ in your own model so a 10-15% appraisal haircut doesn't kill the deal.