The Quick Read: The savings equal what a refinance would cost you on the whole legacy balance, minus what the HELOC costs you on only the cash you draw. A cash-out refinance reprices every dollar you owe at today’s market pricing. A HELOC leaves the old loan alone and prices only the new money. The advantage is largest when the legacy balance is big, the draw is small, and the first lien sits far below market.
- A refinance reprices the entire balance. A HELOC reprices only the draw.
- The saving is a balance-weighted comparison, not a single rate gap.
- Draw size, hold time, and the legacy-to-market spread drive the result.
- On Lendmire’s network, an investment-property line caps at 70% CLTV and $500,000 total.
- A HELOC does not fit every investor. LLC-held property and DTI-constrained borrowers often need the DSCR cash-out route instead.
What Does “Keeping a Sub-4 First Lien” Actually Mean?
A sub-4 first lien is an existing first mortgage carrying a rate below roughly 4%. Keeping it means you leave that loan untouched and pull equity another way. Usually that way is a second lien, a line of credit that sits behind the first mortgage.
How large a line the equity supports.
An equity line is sized by combined loan-to-value, occupancy, and credit — not by rental coverage. Switch the occupancy or the credit band and the ceiling moves with it.
Investment-property lines require a 700 minimum credit score; second-home lines start at a 640 minimum and primary-residence lines at 600, and the combined-LTV ceiling steps down as the credit band drops on primary-residence and second-home lines and holds on investment-property lines; the line cap steps down on primary-residence lines and holds at every tier on investment-property and second-home lines.
A debt-to-income ratio above 45% requires 680+ credit. Profiles under 640 are limited to single-family homes. At least 75% of the approved line is drawn at closing. Ceilings, floors, and caps update from Lendmire’s centralized guideline source.
Line estimate
Illustrative estimate only — not a quote, Loan Estimate, approval, or commitment to lend. The rate is an editable assumption; equity-line pricing is variable through both the draw and repayment periods and never converts to fixed. Occupancy and credit drive the ceiling together: an investment property tops out at 70% combined LTV (minimum credit 700, line cap $500,000); a second home tops out at 90% combined LTV (minimum credit 640, line cap $500,000), with the ceiling stepping down as the credit band drops (the cap holds at every tier); a primary residence tops out at 90% combined LTV (minimum credit 600), and its $750,000 maximum line is available only at 75% combined LTV or below with a 700-or-better credit profile (720 on the longer-runway program) and a full appraisal. Lines above $500,000 require a full appraisal. Credit, debt-to-income, property type, and full underwriting review all affect the final line.
Why does the threshold matter? Because a loan like that cannot be rebuilt in today’s market. Each time you refinance it, the old pricing is gone for good. Investors treat it as a scarce asset, and the whole question here is how much that asset is worth in dollars.
Three terms carry this entire discussion:
- First lien: the original mortgage, paid off first if the property is sold.
- Second lien: a separate loan recorded behind the first one.
- CLTV: combined loan-to-value, meaning all liens added together against the property’s value.
Why the Savings Exist: The Repricing Mechanic
The savings exist because a cash-out refinance replaces your old loan with a new one. The new rate applies to the full balance, including the part you already owed. A HELOC adds a separate loan, so its rate touches only the cash you take.
Think of it as two costs. A refinance costs you the difference between today’s market pricing and your existing pricing, applied to the entire old balance. A HELOC costs you the difference between its own pricing and market first-lien pricing, applied to only the draw. The HELOC wins whenever the first cost is bigger than the second.
Three variables decide that contest:
1. The size of the legacy balance relative to the draw. A big balance and a small draw favor the HELOC.
2. The spread between your legacy pricing and the market. A wider spread means more to lose in a refinance.
3. How long you hold the money. Longer holds expose you to more variable-rate drift on the line.
That is the counterintuitive piece most borrowers miss. A HELOC’s pricing looks worse on paper, yet it applies to far fewer dollars.
The Blended-Rate Formula, Step by Step
The blended rate is a balance-weighted average of your two loans. It gives you one number to compare against a single refinance quote. The steps are simple.
1. Multiply the first-lien balance by its rate.
2. Multiply the HELOC balance by its rate.
3. Add the two results together.
4. Divide by the total debt.
Compare that blended figure to the single rate a cash-out refinance would carry on the same total debt. If the blended number is lower, keeping the first lien costs less at the start.
Here is a purely algebraic illustration with no market numbers. Say the first lien is nine times the size of the draw. The blended rate is then ninety percent legacy pricing and ten percent line pricing. Even if the line costs far more than the legacy loan, it only pulls the average up a little. The refinance, by contrast, moves one hundred percent of the debt to new pricing.
Two warnings apply. The blended rate is a snapshot of day one. It ignores closing costs, and it ignores what happens when a variable line reprices later. Treat it as a starting comparison, not a verdict.
What the Blended Number Hides
Closing costs scale with the loan being written. A refinance writes a new loan for the whole balance, so its costs follow the whole balance. A HELOC’s costs follow the line. The refinance also has to recoup those costs through monthly savings before it breaks even, and if it never does, it was the wrong move.
Check the existing note for a prepayment penalty too. If the first lien is itself a DSCR loan, early payoff charges in the first few years can make a refinance expensive.
Then consider amortization. A refinance restarts the clock on the full balance. A second lien leaves the first loan’s remaining term alone, so you keep the principal you have already paid down.
The line’s own structure changes the real cost as well. The CFPB’s HELOC guide explains that a line has a draw period followed by a repayment period, and that HELOCs usually carry variable pricing. Some plans allow a fixed-rate conversion on part of the balance, which is usually more predictable but costlier than the variable option. The CFPB HELOC brochure adds that interest-only draw periods leave principal untouched, and that variable payments can change even if you draw nothing more.
So the savings are a moving target. They shrink if the line’s index rises or if the draw sits outstanding for years.
How Savings Change With Draw Size and Hold Time
Draw size is the biggest lever. A small draw against a large legacy balance produces a wide advantage for keeping the first lien. The refinance still reprices everything, while the line prices a sliver.
As the draw grows relative to the legacy balance, the advantage narrows. At the extreme, if you are pulling more than you currently owe, the legacy loan is a small part of the picture and the refinance looks less costly by comparison.
| Scenario | Effect on the savings from keeping the first |
|---|---|
| Large legacy balance, small draw | Savings are widest |
| Moderate balance, moderate draw | Savings narrow |
| Small legacy balance, large draw | Savings thin or flip |
| Short hold, then repay the line | Savings hold up |
| Long hold, variable line drifts upward | Savings erode |
| Market pricing falls toward legacy pricing | Refinance gets closer on cost |
To build your own number, run the blended formula three ways: with today’s line pricing, with line pricing a few points higher, and with a larger draw. Where the blended figure crosses the refinance figure is your break-even. Any investor with a long hold should run the higher-pricing version before committing.
Where Keeping the First Lien Breaks Down
The general rule fails in several named situations.
Legacy pricing near the market. If your first lien is close to what a new loan would cost, there is little to protect. The refinance wins.
A large cash need. When the draw is big relative to the existing balance, the repricing advantage shrinks. A refinance can also lock in a fixed structure and remove variable-rate exposure.
A thin line market for rentals. Investment-property lines are narrower than primary-residence lines. On Lendmire’s wholesale network, an investment line requires a 700 credit score at minimum and caps at 70% CLTV and $500,000 total. Primary-residence lines reach higher CLTV tiers and larger sizes, so the route is not equally open to every borrower. Final terms depend on the lender’s guidelines, the property type, and the borrower’s complete credit picture.
Title held in an LLC. This is the sharpest structural break. On the network’s HELOC programs, LLCs, corporations, partnerships, and land trusts cannot hold title. Only an individual or a revocable living trust can. A rental already deeded to an entity needs a vesting change, or a DSCR cash-out refinance instead.
Underwriting basis. A home equity line qualifies the borrower on personal debt-to-income and credit. The maximum DTI is 50%, and the line is qualified on the interest-only payment at the maximum draw. A DSCR loan is reviewed primarily on property-level rental income covering the payment, subject to lender guidelines. An investor who cannot clear DTI may find the keep-the-first route closed even where the math favors it.
Availability. Lendmire arranges these lines in its 16 full-service states only, narrower than its 41-market DSCR footprint.
How the Network’s Lines Are Structured
Lendmire brokers HELOCs through select wholesale partners, so the terms below come from the network, not a single lender. A line can sit in first or second lien position, and the sizes run from $25,000 to $750,000. Investment lines are limited to $500,000, with no tier above that.
On an investment property, the draw structure is a 5-year interest-only period followed by a 25-year fully amortizing repayment. At least 75% of the line is drawn at closing, and pricing floats through both periods without converting to fixed. The line is a variable-cost instrument for its entire life.
Primary residences and second homes have two structures available, including a 3-year draw with a 17-year repayment. Credit tiers matter as well. On a primary residence, 720 or better unlocks up to 90% CLTV on lines to $500,000. That tier does not exist for investment property.
Ineligible collateral is not offered on these programs. That includes manufactured homes, co-ops, condotels, log homes, commercial, mixed-use, and agricultural zoning. All figures are subject to lender guidelines and full file review.
When a Cash-Out Refinance Still Wins
A refinance is the better call in a defined set of cases:
- Your legacy pricing is at or near market, so nothing is being given up.
- You need more proceeds than a $500,000 investment line allows.
- You want a fixed payment and no variable-rate exposure.
- The property is held in an LLC, or your DTI cannot support a personal line.
- You are consolidating several loans into one structure.
For standard rentals, the DSCR cash-out route generally tops out around 75% LTV across most of the network, with about 6 months of seasoning as the common expectation. Short-term rental collateral usually sits lower, around 70%. Coverage of 1.00 is where many select programs start, and a separate select-lender path takes coverage below 1.00 with leverage and terms adjusted. Clearing 1.00 does not mean the property cash flows, because repairs, vacancy, management, and capex sit outside the ratio.
The DSCR path suits entity-held portfolios, borrowers constrained on DTI, and anyone needing more proceeds than a line allows. The HELOC path suits an investor with strong personal income, a modest draw, and a first lien worth protecting. Lendmire’s complete DSCR loans guide walks through how the first-lien refinance side qualifies. For the timing side of the same decision, see Lendmire’s piece HELOC Timing for Homeowners Keeping a Sub-4% First Mortgage.
Which Investors Benefit Most
The investor who gains most holds a low-rate first lien in their own name, needs a modest draw, and has the income and credit to qualify personally. That is a W-2 or otherwise well-documented borrower with one or a few properties.
For that borrower, the HELOC is usually the working lane, because it leaves the legacy first lien in place rather than repricing the balance.
A third route exists. Equity in a home you live in can be drawn and used on a rental purchase. That is a different lien and different collateral, and the primary-residence tiers apply, not the investment ones. 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. For a deeper look at paying down versus drawing, Lendmire’s article Second-Lien HELOC vs Extra Payments When Keeping a Sub-4% Mortgage covers that decision.
Key Terms Defined
Blended rate: the balance-weighted average of your first-lien and second-lien rates.
CLTV: the total of all liens divided by the property’s value.
Draw period: the stretch when you can borrow from the line, often interest-only.
Repayment period: the stretch after the draw ends, when principal is paid down.
Prepayment penalty: a fee some notes charge for paying off a loan early.
DSCR: rental income divided by the full monthly housing obligation.
Frequently Asked Questions
Does a HELOC change my first mortgage?
No. A HELOC is a separate lien recorded behind the first, so the original loan keeps its rate, term, and remaining balance. A line can also sit in first position on some structures, but when you already hold a first lien, the line is the second.
Do I lose my existing first-lien terms in a cash-out refinance?
Yes. A cash-out refinance replaces the old loan with a new one, so the new pricing applies to the entire balance, including what you already owed. That is the core reason investors with a favorable existing first lien look hard at a second lien first.
What if the line’s pricing rises?
The savings shrink. Lines on the network float through the draw and repayment periods and never convert to fixed. The longer you hold a large draw, the more drift matters, so run a higher-pricing version of the blended formula before you commit.
Can I use this strategy on a rental held in an LLC?
Not through these lines. Title must sit with an individual or a revocable living trust, and entities cannot hold it. A property already in an LLC needs a vesting change or a DSCR cash-out refinance, subject to program terms.
How much can I draw on an investment property?
Lines cap at $500,000 total and 70% CLTV, with a 700 minimum credit score. Credit, equity, and the full file decide the actual amount.
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.
About Lendmire
Lendmire is a mortgage brokerage (NMLS# 2371349) arranging home equity lines of credit — primary-residence, second-home and investment-property lines — through a wholesale lending network in its 16 full-service states. Eligibility is determined by the lender on each file. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.
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References
This article is part of Lendmire’s home equity line of credit program — full qualification details, guidelines, and scenarios live on the program page.
Related reading: How to Keep a First-Position HELOC Through a Later Refinance · How to Weigh a VA Cash-Out Against Keeping Your VA Loan and a HELOC · VA Cash-Out vs HELOC for Debt When the First Mortgage Is Worth Keeping
Brandon Miller
Founder & CEO, Mortgage Loan Originator, Lendmire LLC
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Required disclosures. Lendmire (NMLS# 2371349) operates as a licensed mortgage broker, not a direct lender or depository. The discussion in this article is general in nature and should not be relied upon as financial, legal, or tax advice — every investment scenario is unique and should be reviewed by a qualified professional. Any loan inquiry is subject to lender underwriting, and this article is not a commitment to lend or a guarantee of approval. Mortgage rates, loan terms, and program guidelines vary by borrower, property, and state, and may change without notice. Equal Housing Opportunity. Verify licensure at NMLS Consumer Access.