Neither is universally better. The right structure depends on the specific deal economics, the investor’s hold timeline, and whether IO is needed to achieve standard DSCR qualification.
IO or 30-Year? We’ll Model Both for Your Property.
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Mbanc NMLS #38232 | Equal Housing Opportunity Lender
The Payment Comparison
On a $320,000 DSCR loan at 8.25% rate:
| Structure | Monthly Payment | Annual Principal Paid (Yr 1) | DSCR Impact |
|---|---|---|---|
| 30-year amortizing | $2,407 | ~$870 | Lower DSCR |
| 40-year amortizing | $2,264 | ~$460 | Higher DSCR |
| IO (interest-only) | $2,200 | $0 | Highest DSCR |
IO payment vs 30-year: $207/month lower. On a $2,800/month rent property with $800/month in taxes and insurance: PITIA improvements:
– 30-year PITIA: $3,207. DSCR: $2,800 ÷ $3,207 = 0.87 (no-ratio)
– IO PITIA: $3,000. DSCR: $2,800 ÷ $3,000 = 0.93 (no-ratio, but better)
– Increase rent: not possible. Decrease price: already negotiated. IO doesn’t get this deal to 1.00 standard DSCR.
But at 75% LTV ($240,000 loan):
– 30-year PITIA: $2,605. DSCR: $2,800 ÷ $2,605 = 1.07 (standard)
– IO PITIA: $2,450. DSCR: $2,800 ÷ $2,450 = 1.14 (standard, better)
When IO Moves a Deal from No-Ratio to Standard
The deal that matters most for IO: a borderline deal where 30-year amortization produces 0.95–0.99 DSCR (no-ratio) and IO moves it above 1.00 (standard).
Example: $380,000 property. Rent $2,600/month. At 80% LTV ($304,000 loan):
– 30-year P&I: $2,285. PITIA: $3,185. DSCR: $2,600 ÷ $3,185 = 0.82 (no-ratio)
– IO P&I: $2,090. PITIA: $2,990. DSCR: $2,600 ÷ $2,990 = 0.87 (still no-ratio)
Neither gets to standard at 80% LTV on $2,600 rent. At 75% LTV ($285,000 loan):
– 30-year P&I: $2,145. PITIA: $3,045. DSCR: $2,600 ÷ $3,045 = 0.85 (no-ratio)
– IO P&I: $1,959. PITIA: $2,859. DSCR: $2,600 ÷ $2,859 = 0.91 (still no-ratio)
At 70% LTV ($266,000 loan):
– 30-year P&I: $2,001. PITIA: $2,901. DSCR: 0.90 (no-ratio)
– IO P&I: $1,829. PITIA: $2,729. DSCR: 0.95 (no-ratio, but better)
This deal can’t hit standard DSCR at any LTV on $2,600 rent — it’s a no-ratio deal regardless of amortization. IO still improves DSCR and reduces monthly burden, but the fundamental math doesn’t change at this rent/price combination.
Where IO changes the qualification: A deal at $350,000 property, $2,600 rent, at 70% LTV ($245,000 loan):
– 30-year PITIA: $2,742. DSCR: $2,600 ÷ $2,742 = 0.95 (no-ratio)
– IO PITIA: $2,582. DSCR: $2,600 ÷ $2,582 = 1.01 (standard!)
$160/month IO advantage crossed the standard DSCR threshold. Standard vs no-ratio: saves the investor from 30% down (IO) vs accepting 30% down (30-year no-ratio).
The IO Trade-Off: No Equity Build During IO Period
This is the honest cost. For every month in the IO period:
– No principal is paid
– The loan balance stays exactly the same
– No equity is built through amortization (though appreciation may still build equity)
On a $280,000 IO loan at 8.25% over a 7-year IO period:
– Equity built via amortization: $0
– Loan balance at IO expiry: $280,000
On the same loan fully amortizing:
– Equity built via amortization over 7 years: approximately $18,200
The IO investor sacrifices $18,200 in equity build over 7 years for approximately $195/month in lower payments ($195 × 84 months = $16,380 in payment savings).
The math is close — the IO investor gives up slightly more in equity than they save in payments on a nominal basis. The investor who values current cash flow over equity build, or who plans to sell before the IO period expires, favors IO. The investor building long-term equity favors 30-year.
IO After the IO Period: The Conversion Risk
When the IO period expires (year 5 or year 7), the loan converts to fully amortizing on the remaining balance — now amortized over the remaining loan term (25 or 23 years, not 30).
The payment jump:
$280,000 IO ARM: IO payment $2,090/month at 8.25%.
At IO expiry, amortizing the $280,000 balance over 23 remaining years at the then-current ARM rate:
– If rate is unchanged (8.25%): P&I $2,389/month — jump of $299/month
– If rate is higher (10%): P&I $2,804/month — jump of $714/month
The investor who planned for the IO conversion in their long-term hold model handles this adjustment. The investor who didn’t plan for it faces a payment shock that significantly changes cash flow.
When this matters: IO DSCR on an ARM means: ARM rate risk + IO conversion payment jump. Both happen at year 5 or 7. The investor who plans to refinance before IO expiry (or who expects rates to be lower) neutralizes this. The investor who plans to hold past IO expiry on a floating rate is accepting meaningful payment uncertainty.
Who Should Use IO DSCR
Yes to IO:
– Investors who need IO to achieve standard DSCR (1.00+) vs no-ratio
– Investors maximizing short-term cash flow on a planned 5-7 year hold
– BRRRR investors who will refinance at IO expiry into a new DSCR
– Investors where the $200+/month payment savings makes a material difference
Yes to 30-year:
– Investors in long-term hold (7+ years) who want payment certainty
– Investors prioritizing equity build over cash flow maximization
– Investors where the deal qualifies at standard DSCR on 30-year and IO adds no qualification benefit
IO requirements: 660+ credit score. Available on ARM products (5/6 or 7/6 ARM). Not available on 30-year fixed.
FAQ
Is IO available on a fixed-rate DSCR loan? Generally no — IO is typically on ARM products (5/6 or 7/6 ARM). The ARM structure provides the lender with rate adjustment capacity to pair with the IO period.
Does IO have a higher rate than 30-year fixed? IO ARM rates are not directly comparable to 30-year fixed because they’re different product types. IO ARM is typically quoted vs ARM benchmarks. There may be a modest rate premium for IO.
Can I refinance out of IO before the IO period expires? Yes, subject to any prepayment penalty terms. Many investors refinance IO ARM DSCR loans into new fixed-rate DSCR at or before IO expiry.
About the Author: Mayer Dallal — Managing Director, Mbanc NMLS #38232. [mbanc.com/blog/author/mayer-dallal/]
Not a commitment to lend. Mbanc NMLS #38232 | Equal Housing Opportunity Lender
30-Year DSCR vs Interest-Only: Real Numbers and Decision Framework
On a $240,000 DSCR loan at 8.00%:
30-year fully amortizing:
Monthly P&I: $1,761.
After 5 years of payments: loan balance reduced to approximately $224,000. $16,000 in principal paid.
After 10 years: balance approximately $203,000. $37,000 in principal paid.
Interest-only (IO) for first 10 years:
Monthly IO payment: $1,600.
Monthly savings vs 30-year: $161.
After 10 years: loan balance still $240,000 — no principal paydown during IO period.
After year 10: converts to 20-year fully amortizing — P&I jumps to approximately $2,012/month.
The DSCR impact:
$1,761 (30-yr) vs $1,600 (IO) in P&I:
With $2,100/month rent and $238 taxes/insurance: 30-yr PITIA $1,999, DSCR 1.05. IO PITIA $1,838, DSCR 1.14.
IO improves DSCR by 0.09 on this example. For a property near the DSCR floor (0.95–1.00), IO can be the difference between qualifying and not.
When IO makes sense for DSCR:
Property is at the DSCR boundary — IO gets it over 1.00.
Investor plans to sell within 7–10 years (before IO period ends and payment jumps).
Cash flow optimization is priority (higher monthly net income from IO).
When 30-year fixed makes more sense:
Long-hold investor building equity (30-year amortizes principal from Day 1).
Rate certainty matters more than cash flow optimization.
DSCR comfortably above 1.00 — IO savings are nice but not required.
Not a commitment to lend. Mbanc NMLS #38232 | Equal Housing Opportunity Lender
The IO vs 30-year decision comes down to hold period and DSCR ratio. Near the DSCR floor with a medium-term hold: IO optimizes cash flow and qualifies the loan. Long hold with comfortable DSCR: 30-year builds equity and provides certainty. Neither is universally right — the math of each specific property determines which is optimal.
Not a commitment to lend. Mbanc NMLS #38232 | Equal Housing Opportunity Lender | DSCR: qualifying rent ÷ PITIA | 640 minimum credit | Programs and rates subject to change
Mbanc offers both 30-year fixed and interest-only DSCR loan products. The rate premium for IO is typically 25–50 bps above the 30-year equivalent. For most investors: 30-year fixed for long-hold portfolio building, IO for properties near the DSCR threshold or medium-term holds. Both programs available — run both calculations before selecting.