How to Calculate DSCR: Step-by-Step Formula for Florida Rentals (With Examples)

Every declined DSCR file I review has the same root cause: the investor calculated the ratio one way, and the underwriter calculated it another. The formula itself takes ten seconds. Getting the inputs right — especially in Florida, where insurance and reassessed taxes routinely blindside out-of-state buyers — is where deals are won and lost.

This guide walks the calculation exactly the way a lender will run it, with real Florida numbers, three worked examples, and the structuring levers that rescue a failing ratio. Run your own deal alongside it with the free calculator on our homepage.

The DSCR Formula

DSCR = Gross Monthly Rental Income ÷ Monthly PITIA

That's the entire formula for residential (1–10 unit) DSCR loans. Two definitions matter:

• Gross rental income — the full rent, before any expenses. Not net operating income; commercial DSCR uses NOI, residential DSCR does not.
• PITIA — Principal + Interest + property Taxes + Insurance (hazard, wind, and flood where required) + Association dues.

A ratio of 1.0 means rent exactly covers the payment. 1.25 means 25% cushion. 0.90 means the property runs $10 short per $100 of payment. Interpretation tiers, and what each unlocks, are in what is a good DSCR ratio.

Step 1: Establish the Income Number (The One You Don't Control)

Here's what surprises first-timers: your rent projection is never the qualifying number. Lenders accept exactly three sources:

• The 1007 rent schedule. The appraiser researches comparable rentals and issues a formal market-rent opinion alongside the valuation. On vacant properties this carries the entire income side — see DSCR on vacant properties and the full 1007 guide.
• Your executed lease. On tenanted properties, most lenders use the lower of the lease or the 1007 (some accept a lease modestly above market with support). Month-to-month tenancies and family-member leases get extra scrutiny.
• Documented short-term rental revenue. For Airbnb/VRBO properties, 12 months of platform statements, typically averaged monthly. In 2026 most lenders stopped accepting projection-tool estimates at face value — the rules are in using Airbnb income to qualify.

The practical discipline: before you write an offer, pull 3–5 actual rental comps within a mile and similar bed/bath count, and use the conservative middle — not the listing agent's pro forma. If your deal only works at the top rental comp, it doesn't work.

Step 2: Build the True PITIA (The One That Kills Florida Deals)

Each component, with the Florida-specific trap attached:

Principal & interest

Straightforward amortization — but use a realistic DSCR rate for your tier, not an advertised best-case teaser. As of mid-2026 that's generally the mid-6s to mid-7s depending on your tier (current ranges in DSCR rates in Florida). Quick reference at 30-year amortization, per $100,000 borrowed: $633/month at 6.5%, $658 at 6.875%, $682 at 7.25%, $699 at 7.5%.

Property taxes — use the reassessed number

Florida reassesses at sale, and a homesteaded seller's tax bill can be dramatically lower than yours will be. The trap: using the seller's $2,900 bill when your post-sale bill will be $4,700. The fix: estimate 0.83%–1.10% of your purchase price annually by county (most Florida county property appraisers publish a purchase-price-based estimator — use it).

The consolation prize: once you own it, non-homestead assessments are capped at 10% annual growth — see Florida property taxes for investors.

Insurance — the deal-decider

Florida landlord insurance averages roughly $5,400/year statewide for $300K of coverage — more than double the national average — but the range is what matters: roughly $3,000–$4,500/year inland and Central Florida, $5,300–$7,500 coastal South Florida for comparable dwellings, with 2026 finally bringing the first broad rate relief since 2019.

Underwrite the high end of your region's band and get a real quote the day you go under contract. Regional detail: insurance in Florida DSCR deals.

Flood insurance — if mapped, it's in the ratio

FEMA zone A/V properties require flood coverage, and it counts in PITIA. A $1,800/year flood policy is a $150/month ratio hit. Check the flood map before you offer — see flood zones and DSCR.

Association dues — the full amount, always

Condo and HOA dues count at 100%, and in Florida's post-SB-4-D condo market, dues have risen sharply in older buildings funding their reserves. A $650/month assessment needs $650 of extra rent just to hold your ratio flat — context in Florida condo DSCR.

Step 3: Divide and Interpret

Worked Example 1: Long-Term Rental (Port St. Lucie SFH)

$355,000 purchase, 20% down ($284,000 loan) at 6.875% on a 30-year fixed:

Approvable at standard pricing. Note that a $130/month insurance surprise would drop it to 0.996 — under the line. This is why the quote comes first. Market context: Port St. Lucie DSCR guide.

Worked Example 2: Short-Term Rental (Kissimmee Vacation Home)

$480,000 six-bedroom near the parks, 25% down ($360,000 loan) at 7.5% (STR pricing tier):

• PITIA: P&I $2,517 + taxes $420 + STR insurance $410 + HOA $310 = $3,657/month
• On long-term market rent ($3,100 per the 1007): DSCR = 0.85 — fails the standard test
• On documented STR revenue (12-month Airbnb statements averaging $5,350/month): DSCR = 1.46 — strong approval with an STR-income lender

Same house, two ratios — the entire vacation-rental financing game lives in that gap, and it's why lender selection decides these files. The rules for which income counts are in the Airbnb financing playbook and the Kissimmee guide.

Worked Example 3: 2–4 Unit Multifamily (Jacksonville Triplex)

$465,000 triplex, 25% down ($348,750 loan) at 7.125%. All three units count:

• Income: $1,250 + $1,250 + $1,175 = $3,675/month (two leases + 1007 on the vacant unit)
• PITIA: P&I $2,350 + taxes $395 + insurance $340 = $3,085/month
• DSCR = 1.19 — comfortable approval

Multifamily's advantage in the formula: three income streams against one payment stack. The tradeoffs (slightly tighter LTV, higher reserves) are in multifamily DSCR loans; market context in the Jacksonville guide.

The Interest-Only Wrinkle (A Legal Ratio Boost)

On interest-only programs, many lenders qualify on the IO payment.

Rerun Example 1 with a 10-year IO period at 7.0% (IO pricing): the payment drops from $1,866 to $1,657 — PITIA falls to $2,273 and the DSCR rises from 1.05 to 1.14.

On borderline files this single structure change is the difference between decline and approval, and between pricing tiers. Not every lender qualifies on the IO payment, so this is a placement question — mechanics in interest-only and 40-year DSCR loans.

What's NOT in the Lender's Formula (But Should Be in Yours)

The qualifying math deliberately ignores real costs: vacancy (Florida statewide runs near 10% in 2026), property management (8–10% long-term, 20–30% STR), maintenance, capex reserves, utilities, and leasing fees. A 1.05 DSCR property is approvable and also, after true expenses, roughly break-even or slightly negative on cash flow.

My rule for clients: qualify at 1.0+, but buy at 1.20+ on conservative rent — or have a specific reason (appreciation thesis, STR upside, planned value-add) why thinner coverage is acceptable. The lender's formula tells you whether you can close; your formula tells you whether you should.

Seven Mistakes That Break the Calculation

• 1. Using the seller's tax bill instead of the post-sale reassessed estimate — the silent 0.03–0.06 ratio hit.
• 2. Guessing insurance from national averages — quote it in your actual ZIP, wind included, before you offer.
• 3. Forgetting flood — check the FEMA map; zone A/V adds a policy to PITIA.
• 4. Using asking rent instead of comp rent — the 1007 doesn't care what the listing says.
• 5. Netting out expenses — residential DSCR is gross rent over full PITIA; "adjusting" either side just gives you a number no lender will use.
• 6. Running an advertised teaser rate — price the deal at a realistic DSCR rate for your tier (credit, LTV, ratio, property type), not the best-case number from a banner ad.
• 7. Ignoring dues trajectory on condos — a building about to fund reserves post-milestone-inspection will not have today's dues next year; see the milestone inspection law.

Six Ways to Fix a Failing Ratio

• 1. Larger down payment. Every 5% down cuts P&I roughly proportionally — the bluntest, most reliable lever.
• 2. Interest-only structure. As above — often worth 0.08–0.12 of ratio.
• 3. 40-year amortization. Smaller effect than IO, still meaningful.
• 4. Buy down the rate. Points lower the payment permanently — break-even math in rate buydowns.
• 5. Attack the insurance quote. An independent agent shopping 5+ Florida carriers, plus wind-mitigation credits (roof shape, shutters, sealed decking), routinely saves $50–$150/month — real ratio points.
• 6. Switch to a low-ratio program. If the deal genuinely makes sense below 1.0 (heavy value-add, STR upside), low- and no-ratio programs exist for exactly this.

And the seventh option nobody wants to hear: renegotiate the price or walk. The formula is trying to tell you something about the deal.

Florida PITIA Benchmarks by Region (Per $300K Purchase)

To sanity-check your inputs before you have quotes in hand, here's how the tax-and-insurance stack typically lands on a $300,000 single-family purchase across Florida's regions in 2026 — monthly figures, wind included:

*Assumes 20% down at 6.875% (P&I $1,575 on $240,000). Ranges are planning benchmarks — your county appraiser's estimator and a live insurance quote replace them the moment you have a real address.

Read the last column and Florida's DSCR geography becomes obvious: the same $300K house needs roughly $300/month more rent to break 1.0 on the South Florida coast than inland. That's the whole reason market selection guides like the best cash-flow markets in Florida exist.

DSCR vs Cash-on-Cash: The Two Numbers Investors Confuse

DSCR answers the lender's question — does rent cover the payment? Cash-on-cash answers yours — what return does my invested capital earn? They move differently, and optimizing one can hurt the other.

Take the Port St. Lucie example above (1.05 DSCR, $71,000 down plus ~$12,000 closing costs). Gross annual rent of $31,200 minus PITIA of $29,784 leaves $1,416 before vacancy, maintenance, and management — realistic first-year cash-on-cash near zero.

Now put 30% down instead: DSCR jumps to 1.19 (nicer approval, better pricing), but you've parked $35,000 more capital to earn a few thousand a year — cash-on-cash on the extra capital is weak. The reverse trade — maximum leverage via a 15%-down program — maximizes cash-on-cash if the ratio survives, which in high-insurance regions it often doesn't.

The discipline: use DSCR to structure the loan, cash-on-cash to judge the investment, and never let a qualifying ratio stand in for an underwriting decision. A 1.0 that qualifies and a deal worth doing are different claims.

When the Underwriter Re-Runs Your Number (And What To Do)

Your calculation gets you to contract; the lender's calculation gets you to closing, and it can change mid-file three ways:

• The 1007 comes in under your rent figure. The most common re-run. Options, in order: challenge with better comps through a formal reconsideration of value (works when the appraiser missed true comparables), restructure (more down or IO) to pass at the lower rent, switch to a low-ratio program, or renegotiate price with the seller using the appraisal as leverage.
• The insurance binder beats the estimate — in the wrong direction. If the bound premium exceeds what was underwritten, the ratio recalculates at clear-to-close. Prevention is the only cure: real quotes early, and a broker who underwrote your file at the quote, not a placeholder.
• The tax estimate gets corrected. Good lenders underwrite Florida purchases at the reassessed estimate from the start; if yours ran the seller's homesteaded bill, expect the correction — and the ratio hit — in underwriting. Ask which figure was used at pre-approval.

The pattern across all three: surprises come from optimistic inputs, and every one is preventable in the first 48 hours of the file. It's also the honest case for working with a broker who runs Florida files daily — we underwrite your ratio the pessimistic way on day one so the underwriter's version matches ours on day eighteen.

Ratio Sensitivity: What Each $50 Is Worth

A useful mental model for negotiating and structuring: on a typical Florida file with a PITIA around $2,500, every $50/month change in either direction moves the ratio by roughly 0.02.

That means: a $50 insurance saving from wind-mitigation credits ≈ +0.02; a $100/month rent difference between comps ≈ ±0.04; a 0.25% rate improvement on a $300K loan ≈ +0.04; and a $10,000 price reduction at 20% down ≈ +0.02 on payment alone.

Stack three small wins — a sharper insurance quote, a modest price negotiation, one pricing-tier improvement — and a 0.96 file becomes a 1.05 file without changing the property at all. This is what "structuring" actually means in practice, and it's why the difference between a declined file and a funded one is usually assembled $50 at a time.

Keep the payment factors handy for quick mental math: at 30-year amortization, each $100,000 borrowed costs $633/month at 6.5%, $658 at 6.875%, $682 at 7.25%, and $699 at 7.5% — and each $100,000 at interest-only costs simply the rate ÷ 12 (e.g., $573 at 6.875% IO).

With those two facts and your regional tax-and-insurance benchmark from the table above, you can screen any Florida deal to within a point or two of the underwriter's number before you've finished your coffee.

The Bottom Line

DSCR math is simple; DSCR inputs are where Florida deals succeed or fail. Use the 1007-realistic rent, the reassessed tax number, and a real regional insurance quote, and your calculation will match the underwriter's — which means no surprises between contract and closing.

Want the calculation run properly on a specific address? Send it over — we'll price it across our wholesale panel with real figures, free and with no hard credit pull. Start here or call us at (800) 355-ALEX.

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About the Author — Alex Doce, NMLS #13817

Alex Doce is the Principal Mortgage Broker at The Doce Mortgage Group (NMLS #2638131) in Fort Lauderdale, a nationally ranked top-1% originator with 38+ years in Florida lending, 7,000+ closings, and 1,500+ five-star reviews. He has financed Florida investment property through every market cycle since 1987. More about Alex →