How to Run the DTI Math Before Using a HELOC to Buy All Cash

The Quick Read: Running the numbers means passing two separate tests, a personal debt-to-income test on the equity line itself and then a second test on the purchase, which is a source-of-funds review for a true cash buy and a DSCR or DTI review if a mortgage is added. A HELOC is borrowed money, so lenders and sellers may treat it differently than cash in the bank.

• The line is underwritten on your personal credit, income, and existing debt, not on the rental’s income.
• On Lendmire’s wholesale network, the line is qualified on the interest-only payment at the maximum draw, even if you draw less.
• A line on an investment property is capped at 70% CLTV, and a line on a primary residence reaches 90% CLTV only at a 720-or-better credit profile.
• A DSCR purchase loan ignores the HELOC payment in its ratio, but every later DTI-based application will count it.
• Clearing 1.00 coverage is not the same as positive cash flow.

Why Does a HELOC-Funded Purchase Need Two Approvals?

A HELOC-funded purchase needs two approvals because the equity line and the property are judged by different tests. The line asks whether you can carry the debt personally. The purchase asks whether the property, or the combined debt, holds up.

Many investors assume that borrowing against a home to pay cash skips scrutiny. It skips the purchase mortgage, not the line. Across the wholesale network, the equity line is a personal credit decision, with a 50% DTI ceiling on most files. The investor’s rentals, mortgages, car loans, and cards all feed that ratio.

There are two ways to run the second test. A pure cash purchase has no new mortgage, so the second test is mostly documentation of where the money came from. A mortgage-assisted purchase adds a DSCR or DTI-based loan on top of the line. Each path is covered below.

The DTI Math, Step by Step

The DTI math has five steps: total your monthly debts, divide by gross income, add the new line payment, check the result against the program ceiling, then stress it. Run it before you shop for the line, because a failed ratio is cheaper to learn about early.

1. Total your current monthly debts. Include every payment on your credit report: mortgages (including financed rentals), auto loans, student loans, and card minimums.

2. Divide by gross monthly income. Use pre-tax income. That gives your baseline DTI.

3. Add the new HELOC payment. On this network, that payment is the interest-only amount calculated on the maximum draw. A lightly drawn line can still weigh heavily on the ratio.

4. Divide again. Add the HELOC payment to the debt total and divide by the same gross income. That is your post-line DTI.

5. Compare it to the ceiling. The network maximum is 50%. It is 45% for credit profiles from 600 to 679. A ratio above 45% requires a 680 minimum score.

Rental income can help the ratio, and existing rental mortgages can hurt it. A heavily financed portfolio therefore shrinks the line you can get. The network also limits a borrower to three lines, and a borrower owning more than 15 financed properties is not eligible.

A Worked Example

These ratios are illustrative assumptions, not market data. Subject to lender guidelines and full file review, the read looks like this.

The third row shows the usual failure. The fix is a smaller line, paying down a card or auto loan first, or documenting more income. Drawing less after approval does not help, because the qualifying payment assumes the full draw.

How Big Can the Line Be?

The line size equals property value times the CLTV cap, minus what you already owe. CLTV counts every lien on the home, so a first mortgage and the new line both go into the formula. The cap depends on occupancy and credit.

Lower credit tiers on a primary residence step down from there, to 80% at 640+, 70% at 620+, and 60% at 600+. The “longer-runway structure” is a 5-year interest-only draw followed by a 25-year repayment. The other structure is a 3-year draw with a 17-year repayment. Investment lines use only the 5-year draw and 25-year repayment structure.

At least 75% of the line must be drawn at closing, and the line’s pricing floats for the whole term. Lines at or below $500,000 usually use an automated valuation instead of a full appraisal. HELOC placements are limited to Lendmire’s 16 full-service states, narrower than the 41-market DSCR footprint.

Title matters too. The individual borrower or a revocable living trust must hold title. An LLC cannot, so a rental already deeded to an LLC needs a vesting change or a DSCR cash-out refinance instead. The line also excludes manufactured homes, co-ops, condotels, and log homes.

Which HELOC Payment Counts?

The payment that counts is the interest-only payment on the maximum draw, not on your actual balance. Different assumptions move the DTI in different directions, which is why asking the lender how it counts the line is the first question to answer.

The repayment phase is the stress point. When the draw period ends, the payment resets to fully amortizing. A ratio that clears comfortably today can look tight at that reset, so run the amortizing version as your stress test.

What Changes If You Add a Mortgage?

If you add a purchase mortgage, the second test depends on the loan type. A DSCR loan compares rent to the full monthly obligation (principal, interest, taxes, insurance, and any HOA dues) and leaves your personal debt out of the ratio. A DTI-based mortgage puts the HELOC payment and the new mortgage in the same ratio, so the stack gets tall.

DSCR loans are designed for non-owner-occupied investment properties. Because they are business-purpose investor loans, they are reviewed differently from a standard owner-occupied mortgage, as the federal rule on exempt transactions lays out for business-purpose credit. That does not remove lender review of credit, reserves, or the source of funds.

Here is what most DSCR files in the wholesale network look like:

• Purchase leverage commonly lands at 75% to 80% LTV, and select programs reach 85% LTV at roughly a 700+ score.
• Coverage of 1.00 is where select programs start. Stronger ratios open better pricing and leverage. A separate select-lender path takes coverage below 1.00, with leverage and terms adjusted.
• Market rent comes from an appraisal rent schedule: Form 1007 for single-unit properties and Form 1025 for 2 to 4 units.
• Reserves commonly run around 6 months of PITIA, though the count varies by lender, leverage, and loan size.

A HELOC that funds the entire down payment means you are financing close to 100% of the price across two loans. Borrowed money may satisfy the down payment but often not the reserve requirement. Most programs accept documented secured sources such as a HELOC, a second mortgage, or a cash-out refinance, and generally decline an unsecured personal loan. Treatment still varies: some programs cap the borrowed share, and the strictest want a slice of unborrowed funds.

Where the General Rule Breaks

Four edge cases change the answer, so check each against your file.

A rent-qualified HELOC is not a standard product. The nickname “DSCR HELOC” usually describes a closed-end second or a cash-out refinance. A true revolving line is underwritten on personal credit, debt, and equity. A DSCR cash-out refinance can close in an LLC, subject to lender program eligibility.

A DSCR second can break a first loan that clears alone. The lender reviews rent against the combined payments on both loans. A first loan that clears 1.00 by itself can fall short once the second payment is added.

Sequence can sink the deal. Most purchase lenders and sellers expect the line to be open and funded before you go under contract. Starting the line after an offer is accepted puts the deal at risk.

Property count and tax matter. A borrower with more than 15 financed properties is ineligible. Tax treatment can depend on how the funds are used and how the property is held; investors should keep clear records and speak with a qualified tax professional before relying on any deduction.

Stress-Test Beyond the Ratios

Pass the lender’s ratio, then pass your own. Lender approval measures what the file can bear, not what is comfortable.

• Reset test. Recompute your DTI using the fully amortizing payment on the full line.
• Pricing test. The line floats and never converts to a fixed structure, so model a higher payment on the same balance.
• Income test. Cut your gross income by a meaningful share and see where the ratio lands.
• Vacancy test. DSCR compares rent to PITIA only. Repairs, vacancy, management, utilities, and capex all sit outside the calculation, and the HELOC payment is a real obligation outside the coverage number too.

Clearing 1.00 coverage on the rental is not positive cash flow. If the property cannot survive several months of vacancy, the line is probably too big.

After the Purchase: Refinance or Payoff?

The usual exit is a cash-out refinance on the new property that pays off the line. Cash-out refinances top out around 75% LTV across most of the network on standard rentals, and about 6 months of seasoning is the common expectation. Until then, you carry both the line and the property, and the HELOC payment stays on your personal DTI. Final terms depend on lender guidelines, property type, leverage, and the borrower’s complete credit picture.

Whether a refinance right after a borrowed-fund cash purchase qualifies as delayed financing is a separate question. Lendmire’s article Does an All-Cash Buyer Qualify for Delayed Financing After Using a HELOC? works through it. The sharper point is that after a DSCR refinance replaces the line, the personal HELOC payment disappears, but the new loan’s treatment on later DTI applications depends on the program.

Key Terms Defined

DTI (debt-to-income ratio): The Consumer Financial Protection Bureau defines DTI as all monthly debt payments divided by gross monthly income, and notes that limits differ by loan product and lender.

CLTV (combined loan-to-value): All liens on the property added together, divided by its value.

DSCR (debt service coverage ratio): Monthly rent divided by the full monthly property obligation.

PITIA: Principal, interest, taxes, insurance, and any association dues.

Draw period: The stretch when you can borrow from the line and pay interest only. After that, the balance amortizes.

When This Strategy Doesn’t Fit

Skip the HELOC route in four situations.

• Your post-line DTI is above 45% and your score is below 680.
• Your equity sits in an LLC-titled property, which cannot hold a true HELOC.
• The property is a type the line excludes, or the DSCR program does not offer it. Manufactured homes (single- and double-wide), log homes, and barndominiums are not offered in the network’s DSCR programs.
• Your rental portfolio is already heavily financed, since each financed property on your credit report shrinks the next line.

For heavily financed portfolios, a DSCR cash-out refinance on a property that already has equity can be the better route. Lendmire’s complete DSCR loans guide explains how those loans qualify on property-level rental income, subject to lender guidelines.

Next Steps

If you are considering a home equity line and want to see how the numbers work, Lendmire can help you compare HELOC options based on the property, the equity available, credit profile, combined leverage, and your goals. Call 828-256-2183 or request a quote. Qualification is subject to lender guidelines. This is not a commitment to lend.

About Lendmire

Lendmire — NMLS# 2371349 — is a mortgage broker that arranges home equity lines of credit in its 16 full-service states through wholesale lenders, on primary residences, second homes and investment properties. Every line is subject to the lender’s guidelines and full underwriting. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. eCFR: 12 CFR 1026.3, exempt transactions

2. CFPB: What is a debt-to-income ratio?