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
Most DSCR programs require 1.0-1.25. Rate tier improvements at 1.25 and 1.5. Below 1.0 either denies or moves you to a more expensive sub-1.0 product with worse LTV.
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 says 1.30. The lender comes back with 1.08 and a different rate tier. Three usual reasons:
- Appraiser rent < your rent.The lender uses the 1007/1025 form “market rent.” If the appraiser comes in 10% below your number, NOI drops ~10% and DSCR drops proportionally.
- PITIA vs P&I.If you computed on P&I and the lender uses PITIA, expect 0.10-0.20 lower DSCR.
- Lender-imposed vacancy / management add-back.Some lenders deduct 5-10% for vacancy and 8% for management even if you self-manage — to underwrite the property without assuming free labor.
Defense: ask the lender exactly which methodology they use, then build your model that way. If you're targeting a 1.25 DSCR program, underwrite to 1.4+ to absorb the appraisal and methodology haircut without dropping below their minimum.
Stress-test your DSCR
Before applying, run three scenarios:
- Base case with your rent and rate.
- Appraiser comes in 10% under rent— does DSCR still clear the lender's minimum?
- Rate +0.5pp — does DSCR still hold up if rates spike before you lock?
If all three pencil, you're bankable. If only the base case works, you have no margin for the 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?
Most DSCR loan programs require 1.0-1.25 minimum, with rate tier improvements at 1.25 and 1.5. Some 'no-DSCR' or 'sub-1.0' products exist but they carry meaningful rate premiums (1.5-2.5 percentage points above market) and tighter LTVs (65-70% instead of 75-80%). Above 1.25 is comfortable; below 1.0 means the property doesn't generate enough to cover its mortgage and is bleeding cash monthly.
How is the lender's DSCR calculation different from mine?
Three usual differences. (1) Most DSCR lenders use the 1007/1025 form 'market rent' from the appraiser — NOT your lease rent. If the appraiser comes in below your number, the lender's DSCR is lower than yours. (2) Many lenders use PITIA (principal + interest + taxes + insurance + association dues) as debt service, not just P&I. This makes the denominator bigger and DSCR lower. (3) Lenders often haircut your NOI by adding a vacancy and management deduction even if you self-manage. Net effect: the lender's DSCR is usually 5-15% lower than what you calculated.
What's a 1.25 DSCR loan in plain English?
A loan where the property must produce $1.25 of net operating income for every $1 of debt service, i.e. 25% margin. If the mortgage payment is $2,000/month ($24,000/year), the property must produce at least $30,000 of NOI annually to clear the 1.25 threshold. If NOI is lower, the loan either gets denied at 1.25 or shifts to a 1.0-tier product with worse rate and LTV.
Can DSCR be negative?
Mathematically yes if NOI is negative (operating expenses exceed gross rent), but no DSCR lender will fund a deal with negative DSCR — it means the property loses money before the mortgage payment, which is a non-starter. If your DSCR calculation goes negative, you either have operating expenses wildly out of line or unrealistically low rents — re-check both before going further.
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.