Founder, FirstLienHELOC.com
How First Lien HELOC Rates Work
Unlike traditional mortgages that typically use fixed interest rates, first lien HELOCs are generally variable-rate products, although some may offer the option to lock in a fixed rate for a limited period.
The interest rate on a first lien HELOC is typically made up of two components: a financial index plus a lender-defined margin. The index — such as the Prime Rate, 1-Month T-Bill, or 1-Year CMT (Constant Maturity Treasury) — moves up or down based on broader market conditions. The margin is set by the lender and is based on factors such as credit score, loan-to-value (LTV) ratio, and overall borrower qualification. While the index can fluctuate over time, the margin remains fixed for the life of the loan.
Most first lien HELOC programs also require a maximum LTV of around 85%, meaning borrowers must retain at least 15% equity in their home. In general, borrowers with higher credit scores and more equity tend to qualify for lower margins, which results in a lower overall interest rate.
Representative Rate Scenarios
Based on 1-Year CMT index of 4.25% · As of March 2026
View Sample Rates
Click to view editorial rate estimates. You'll be asked to acknowledge these are not real offers from a lender.
Reveal RatesRates shown are representative estimates for illustrative purposes only and are not offers to lend. Your actual rate will depend on your credit profile, equity position, and lender. FirstLienHELOC.com is not a lender.
A 7.5% HELOC paid off in 6 years costs far less total interest than a 6.5% mortgage paid over 30 years. The math is counterintuitive but unambiguous. See the complete interest calculation breakdown.
What Is an Index?
An index is a benchmark interest rate that serves as the foundation for a HELOC's variable rate. First lien HELOC products are commonly tied to widely recognized market benchmarks, which may include U.S. Treasury-based indices (such as the 1-Month T-Bill, 1-Year T-Bill, or 1-Year Constant Maturity Treasury), the Prime Rate, or other published reference rates used in the lending industry. The specific index used is selected by the lender at the time the loan is originated and remains the reference point for the life of the loan.
These indices reflect broader market conditions and are influenced by factors such as Federal Reserve policy, inflation, economic conditions, and supply and demand in the credit markets. As these factors change, the index moves up or down, which in turn impacts the borrower's interest rate. While the index fluctuates over time, the structure of the loan remains consistent, with the borrower's rate adjusting based on the chosen benchmark plus the lender's fixed margin.
Common Treasury Bond Indexes
1-Month T-Bill
The shortest-term treasury index. Closely tracks Federal Reserve policy decisions and adjusts quickly to changes in the federal funds rate. Tends to be more volatile month-to-month.
1-Year T-Bill
A medium-term treasury index that reflects market expectations for rates over the next year. Smoother than the 1-Month T-Bill, offering more predictable rate adjustments.
1-Year CMT
The Constant Maturity Treasury (CMT) is derived from the yield curve of U.S. Treasury securities. The 1-Year CMT is one of the most commonly used indexes for adjustable-rate home loans including first lien HELOCs.
You cannot control the index — it moves with the bond market. What you can influence is your margin, which is determined by your credit score, equity position, and lender. A lower margin means a lower rate regardless of where the index sits. Once locked, your margin never changes.
Understanding Index + Margin
How Your Rate Is Calculated
Your margin is fixed for the life of the loan — it never changes. Only the index rate moves, fluctuating with the bond market. This means your rate will vary over time, but the compressed 5–7 year payoff timeline limits your total exposure to rate variability.
What Determines Your Rate
Your margin — and therefore your rate — depends on several factors. Credit score is the biggest driver: every 20-point increment above 700 typically improves your margin by 0.125–0.25%. Loan-to-value ratio, debt-to-income ratio, property type, and lender competition also play a role.
Rate Tiers by Credit Score
| Tier | Credit Score | Typical Margin | Typical Rate |
|---|---|---|---|
| Excellent | 760+ | +2.25% to +2.75% | 6.50%–7.00% |
| Very Good | 740–759 | +2.75% to +3.25% | 7.00%–7.50% |
| Good | 720–739 | +3.25% to +3.75% | 7.50%–8.00% |
| Fair | 680–719 | +3.75% to +4.25% | 8.00%–8.50% |
Loan-to-value ratio — Most first lien HELOC products require LTV below 85%. More equity means a lower margin; borrowers below 50% LTV get the best pricing.
Debt-to-income ratio — Below 43% is standard; below 36% gets you premium pricing.
Property type — Primary residences get the best rates. Investment properties and second homes carry higher margins.
Lender competition — Rates vary between lenders. Our lender matching compares options for you.
Find the Right Lender for You
We've vetted lenders who specialize in first lien HELOCs and understand the velocity banking strategy. Our matching service connects you with providers offering competitive margins, integrated checking, and the features that matter most for this strategy.
Rate Sensitivity: What If Rates Rise?
This is the most common concern — and the most misunderstood. Because your rate is tied to a treasury bond index, it will fluctuate with bond market conditions. See the complete rate stress test analysis showing results at 7%, 8%, 9%, 10%, and 12%. Even at 12%, velocity banking saves over $262,000 compared to a traditional mortgage. The compressed payoff timeline is the key: you're exposed to rate variability for 5-7 years, not 30.
We monitor index rate trends and update this page as conditions change. Rate examples reflect general market conditions — your actual rate depends on your individual qualification profile. Talk to a lender to see your specific rate options.
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