The Quick Read: Most lenders that offer a lock let you fix some or all of the drawn balance, never the undrawn line, and the fixed slice then pays principal and interest over a set term while the rest keeps floating, and the equity lines Lendmire places through its wholesale network never convert to fixed at all. Locking usually raises the monthly payment on the locked slice, because principal repayment starts. In exchange, that slice stops moving with the index.
- The ceiling is the outstanding balance. You cannot lock money you have not borrowed.
- There is no universal percentage cap. Each lender’s account agreement sets minimum lock sizes, lock counts, and terms.
- The locked slice becomes a fixed installment. The unlocked remainder stays variable.
- On the investment-property lines in Lendmire’s network, the answer is zero. Those lines float for life.
What a HELOC Lock Actually Is
A lock is a feature that converts part of a variable-rate line into a fixed-rate installment segment. It is not a separate loan, and it is not a standard feature of every line.
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.
A home equity line of credit has two phases. During the draw period you borrow and repay as needed, and the minimum payment is usually interest on what you have drawn. After the draw ends, the balance amortizes over a repayment period. The line is variable by default.
A lock, sometimes called a fixed-rate conversion, lets you move a chosen piece of the drawn balance out of the floating pool. Bankrate’s HELOC glossary describes it as converting a portion of the outstanding variable balance to fixed, typically at any time during the draw period.
Two different products get confused here. A line that converts later is a variable line with a lock option. A fixed-rate home equity product from day one is different. It often requires you to take the full amount at closing and usually works more like a standard second mortgage. The mechanics below apply to the first kind.
How Much Can Be Locked?
Percent, Dollars, or Both
There is no national percentage cap, and no single rule covers all lenders. The ceiling is the drawn balance, and the lender’s agreement sets everything below that ceiling.
Many people expect a percentage answer, such as “you can lock 80%.” Lender terms rarely work that way. Four limits tend to do the real work:
1. Drawn balance. The lock cannot exceed what you have actually borrowed. Undrawn credit cannot be locked.
2. Minimum lock size. Lenders set a floor, because tiny installment segments cost too much to service. A small drawn balance may not qualify at all.
3. Number of active locks. Many lenders cap how many locked segments can exist at once. Each new lock uses one of the slots.
4. Term menu. You pick from the repayment terms the lender offers, and the longest term is usually shorter than a first mortgage.
In practice, then, the answer is both. The maximum is a share of the drawn balance, up to all of it. The minimum is a dollar floor. The count is a number of slots. Most lenders let you lock some or all of the drawn amount, which matches the CFPB’s plain-language HELOC explainer. It also says the fixed rate is usually higher than the variable rate but more predictable.
A locked slice also keeps using part of your credit limit while it is outstanding. Locking changes how the debt is repaid. It does not enlarge the line.
How the Payment Changes, Step by Step
The payment effect comes from two changes at once: a fixed rate, and a switch from interest-only to amortizing. Most of the jump on the locked slice comes from principal repayment, not from the rate itself.
Here is the sequence on a line that offers a lock.
1. You draw. The balance floats. The payment is typically interest on the drawn amount.
2. You request a lock during the draw period. Most lenders allow conversion only while the draw is open, so the agreement matters.
3. You choose an amount and a term. The lender sets the fixed rate, and pricing varies by scenario and market conditions on the day of the request. That is why two locks on the same line, taken months apart, can carry different fixed rates.
4. The locked slice becomes its own installment. It has a principal-and-interest payment over the term you picked. Some lenders also offer a fixed interest-only option, but amortizing is the common design.
5. The remainder keeps floating. It keeps its own minimum payment and stays exposed to index moves.
6. Your total payment is the sum of the two pieces. That means the fixed installment plus whatever the floating portion costs that month.
Picture an investor with a fully drawn line who locks 60% of the drawn balance and leaves 40% floating. Before the lock, the payment was interest-only on 100% of the balance. After the lock, the 60% slice pays principal and interest on a schedule. The 40% slice still pays floating interest. The combined payment is usually higher than before, and the investor has traded cash flow for certainty.
Term length changes the picture. This table shows direction only, with no figures attached.
| Locked term | Monthly payment on slice | Total interest paid | Best fit |
|---|---|---|---|
| Shorter | Highest | Lowest | Debt you want gone soon |
| Longer | Lower | Higher | Tight monthly budget |
| Fixed interest-only (some lenders) | Lowest | Highest | Short hold, then payoff |
A fixed slice also gives up the upside. Bankrate’s HELOC calculator page notes that a fixed structure protects against increases but forfeits the benefit of declines.
Think of a lock as insurance. You pay a premium in a higher starting cost and a less flexible payment, and you buy predictability.
How to Size a Lock
Lock the amount you expect to carry for a long time, and leave floating the part you plan to repay soon. The right share depends on how long the money will stay outstanding and how much payment volatility your cash flow can absorb.
| Situation | Sensible approach |
|---|---|
| Funds tied to a long-hold purchase or rehab | Lock the project-sized draw; keep a variable cushion |
| Balance you plan to repay soon | Lock little or nothing; the premium rarely pays off |
| Thin monthly cash flow | Lock more, for predictability, accepting a higher payment |
| Strong cash flow and flexible exit | Lock less; keep interest-only flexibility |
Two practical points apply to every case. First, a lock leaves less headroom for later draws, so leave room if you expect to borrow again. Second, a lock with a high minimum can force you to convert more than you intended. If the minimum is larger than the amount you want fixed, the lock may not fit your plan.
(One more thing worth weighing: a lock that is too large can turn a flexible line into a rigid installment loan, and then the line has lost the reason you opened it.)
Where the General Rule Breaks
Several edge cases change the answer.
Not every line has a lock. It is a lender feature, not a legal requirement. Many lenders do not offer it, and lines on rentals are less likely to include it.
Lock-later is not fixed-from-day-one. A line that converts keeps its variable character on everything you do not lock. Later draws return to the variable rate unless you lock them too.
Fees and pricing vary. The CFPB lists a fixed-rate conversion among the fees a line may carry, as the CFPB HELOC brochure explains in its discussion of converting part of a balance. Some lenders charge per lock. Some price a lock higher when it is requested late in the draw.
Rental collateral can price differently. Some lenders add a pricing premium on second or investment homes, so the same lock can cost more on a rental than on a primary residence.
Account status matters. Some lenders bar conversion on lines with a past-due history, and lenders can also restrict or freeze a line under the agreement. Do not assume undrawn credit is guaranteed.
Draw end. Even a variable line’s payment steps up when repayment starts. A lock taken before the draw ends can soften that transition, but only if the agreement allows the request that late.
What Lendmire’s Network Offers
Lendmire is a mortgage broker. It arranges equity lines through select wholesale partners, and the lender sets the final terms. Across the network, none of the lines convert to fixed. Pricing floats during the draw and during repayment.
Here is how the investment-property line is built, subject to lender guidelines and full file review:
- Ceiling: up to 70% combined loan-to-value on an investment property, with a maximum line of $500,000.
- Credit: a 700 minimum credit score on investment lines.
- Structure: a 5-year interest-only draw followed by a 25-year fully amortizing repayment.
- Draw at closing: at least 75% of the line is drawn at closing.
- Qualifying payment: debt-to-income is tested on the interest-only payment calculated on the maximum draw.
- Vesting: title must sit with the individual borrower or a revocable living trust. LLCs cannot hold title on these lines, which is a sharp difference from a DSCR loan.
- Availability: 16 full-service states, a narrower footprint than the DSCR program.
Because at least 75% of the line is drawn at closing, the floating balance is large from day one. Because the structure never converts, the only way to fix the payment is to refinance the line, pay it down, or move the debt to a different product.
Primary-residence and second-home lines in the network follow different tables and offer a shorter or longer draw option. Neither converts to fixed.
Why a Locked HELOC Payment Does Not Change DSCR Coverage
A lock changes your personal cash flow and the line’s payment, but it does not change coverage on a separate DSCR loan. That loan compares rent to its own payment, meaning principal, interest, taxes, insurance, and any association dues.
DSCR is also not a cash-flow measure. Clearing the ratio does not mean the property is profitable, because repairs, vacancy, management, utilities, and capital reserves all sit outside it. A floating line on top of that can make the real picture less predictable than the ratio suggests.
The details depend on the structure. If the line is a second lien on the same property that carries a DSCR loan, the lender reviews the combined debt on that property. If it is secured by a different property, it sits outside the first loan’s calculation. In both cases, the line still counts as debt against the property’s combined loan-to-value.
Many investors who start with a line on a rental later move that debt into long-term fixed financing, because short draws and short amortization schedules can strain cash flow on a long hold. That is a strategy choice, not a rule.
If you are weighing alternatives to a lock, three paths come up most often:
- Refinance into a fixed home equity loan. This replaces the line with a standard installment.
- Cash-out refinance. If the line stays open, the line holder must approve subordination. Lendmire’s piece How Much a Subordinated HELOC Payment Changes After a Refinance walks through that case.
- DSCR cash-out refinance. On a standard rental, cash-out typically tops out around 75% LTV across most of the network, and about 6 months of seasoning is the common expectation. It qualifies primarily on property-level rental income covering the payment, subject to lender guidelines. The complete DSCR loans guide covers how those files are structured.
A DSCR floor of 1.00 is where select programs start. A separate select-lender path takes coverage below 1.00, with leverage and terms adjusted. Strong coverage opens better pricing and leverage, but it does not remove credit floors, reserve rules, or property eligibility. Terms vary by lender guidelines, property type, leverage, credit profile, and full file review.
What Brokers See in Practice
Files with a locked slice tend to go wrong in the same few places. The most common is a lock taken at the wrong time: the investor locks a large share, rates then fall, and the fixed slice sits above the floating alternative for years. The second is a minimum lock size that forces a larger conversion than the investor wanted. The third is a missed deadline. The investor assumes the option survives past the draw period and finds it does not.
The investors who do best treat the lock as a planning tool. They decide the holding period first, then lock only the portion that matches it.
Questions to Ask Before You Lock
Ask the lender these before you request a conversion:
1. What is the minimum amount per lock?
2. How many locks can be active at once?
3. Which terms are offered, and is the slice amortizing or interest-only?
4. Is there a fee per lock, and is there a fee to unlock or re-lock?
5. Can I lock only during the draw, and when exactly does the draw end?
6. Does repaying a locked slice free up available credit again?
7. What happens to the slice at the end of its term or at the end of the draw?
8. Does an investment-property line price differently?
Get the answers in writing. The account agreement, not a website summary, governs the feature.
Key Terms Defined
Draw period: The stretch when you can borrow from the line, usually with interest-only minimum payments.
Repayment period: The stretch after the draw when the balance amortizes and the line is generally closed to new borrowing.
Lock (fixed-rate conversion): A feature that converts part of the drawn balance to a fixed-rate installment.
Locked segment: The portion of the balance that has been converted and now pays on a schedule.
CLTV: Combined loan-to-value, which adds every lien on the property and divides by its value.
DSCR: The ratio of a property’s rent to its monthly debt service, used to qualify investor loans on the property’s income.
Tax treatment varies by how funds are used and how the property is held, so consult a qualified professional before relying on any deduction.
Frequently Asked Questions
Can I lock my whole HELOC balance?
Often yes, on lines that offer the feature, but only the drawn balance. The undrawn line cannot be locked. Some lenders cap the number of locks or set a minimum, so the practical limit comes from the agreement. On the investment-property lines in Lendmire’s network, no lock exists, because pricing floats through the draw and repayment.
Does locking lower my monthly payment?
Usually not. The locked slice typically moves from interest-only to principal and interest, which raises that slice’s payment. A longer term softens the increase and a shorter term sharpens it. The benefit of a lock is predictability, not a smaller bill.
Can I still borrow after I lock part of the balance?
Generally yes, within the remaining available credit, during the draw. Later draws float unless you lock them too. The locked slice uses part of your limit while it is outstanding, and at many lenders, repaying it frees credit again. Confirm that detail in the agreement, since lenders differ.
What happens if rates fall after I lock?
The locked slice stays at its fixed rate. You lose the benefit of the decline on that slice, while the floating remainder keeps adjusting. Some lenders allow an unlock or re-lock, sometimes for a fee, so that is worth checking before you commit.
Why can’t a lender just let me lock the full credit line?
The fixed segment is built from money already borrowed. A lender cannot set a fixed installment on funds that have not been advanced. The undrawn portion remains a variable, revolving option.
Next Step
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. Lendmire arranges DSCR investor loans across 40 states plus Washington, D.C. (41 markets total) through select lenders in its wholesale network, and equity-line placement covers a smaller set of states. Every program is subject to lender guidelines and individual underwriting, and nothing here is a commitment to lend.
An investor who treats the lock as a decision about holding period, not a reaction to the index, will almost always size it better.
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
2. CFPB – What is a home equity line of credit (HELOC)?
3. Bankrate – HELOC calculator
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 Much a Servicing Transfer Can Change on a HELOC? · How to Open a HELOC on a Home Inherited by Siblings · DSCR Refinance on a Tenant Payment Plan vs After Eviction
Brandon Miller
Founder & CEO, Mortgage Loan Originator, Lendmire LLC
- Mortgage Loan Originator · NMLS# 1129696 · Verify on NMLS Consumer Access
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- Lendmire LLC · Firm NMLS# 2371349 · Verify firm licensure
Disclosures. The information presented in this article is general market commentary, not financial, legal, or tax advice. Lendmire is a mortgage brokerage (NMLS# 2371349) — not a direct lender or depository institution — and loan placement is subject to lender underwriting. Nothing in this content represents a commitment to lend. Loan terms, pricing, and program availability vary based on borrower qualifications, property characteristics, and state of subject property, and are subject to change at any time. Lendmire complies with Equal Housing Opportunity requirements. Consumer access: nmlsconsumeraccess.org.