HELOC Affordability Calculator

How Lenders Calculate Your HELOC Limit

The formula is combined loan-to-value (CLTV). Your mortgage balance plus the new HELOC cannot exceed a percentage of your home value that the lender considers safe. In 2026, most lenders cap CLTV at 85%. Borrowers with credit scores above 760 can negotiate 90% CLTV at some credit unions and portfolio lenders. Borrowers below 640 usually see caps at 75% to 80%.

The practical math: if your home is worth $500,000 and you owe $300,000 on the mortgage, you have $125,000 of available HELOC space at 85% CLTV. At 90% CLTV, that jumps to $150,000. The gap between the two is $25,000 — often the difference between a full home renovation and a partial one. ([CFPB](https://www.consumerfinance.gov/consumer-tools/educator-tools/your-home-loan-toolkit/))

Draw Period vs Repayment Period: The Payment Shock

A HELOC runs in two phases. The draw period (usually 5 to 10 years) lets you borrow against the line and typically requires interest-only payments. The repayment period (usually 15 to 20 years) converts the outstanding balance into a fully amortizing loan with principal plus interest.

The payment jump between the two phases is called payment shock. A $100,000 HELOC at 7.28% costs about $607 per month during interest-only draw. When it converts to a 20-year repayment schedule, the payment jumps to roughly $790 per month — a 30% increase. The CFPB documented cases where payments rose more than 35% after the draw ended. Borrowers who budget only for the draw payment are often caught off guard. ([CFPB HELOC booklet](https://www.consumerfinance.gov/ask-cfpb/what-is-a-home-equity-line-of-credit-en-107/))

Credit Score and DTI Requirements

The minimum credit score for most HELOC lenders is 620. Scores below 620 usually fail automated underwriting entirely. The pricing tiers break down into four bands: 620-679 pays margins of Prime + 2% to Prime + 5%, 680-719 pays Prime + 1% to Prime + 2%, 720-759 pays Prime + 0.5% to Prime + 1%, and 760+ pays Prime + 0.25% to Prime + 0.5%.

Debt-to-income (DTI) matters just as much. Most lenders cap total DTI at 43% when the HELOC payment is included. The ideal DTI is below 36%. Borrowers at 45% to 50% DTI can still qualify with compensating factors like large cash reserves or high credit scores. Above 50% DTI, almost all HELOC lenders decline.

Tax Deductibility: The One Rule to Remember

HELOC interest is tax-deductible only when the funds are used to buy, build, or substantially improve the home that secures the loan. Using HELOC funds for debt consolidation, education, vacations, or any personal expense disqualifies the deduction. The IRS tracks this with the "use of funds" test — you must be able to document how the money was spent.

The deduction covers combined mortgage and HELOC debt up to $750,000. For a borrower in the 22% federal bracket with a 7.28% HELOC rate, the after-tax effective rate on deductible interest is 5.68%. That is a meaningful difference: over 10 years on a $100,000 balance, the tax deduction saves roughly $16,000 in interest. Keep receipts, invoices, and contractor records. ([IRS Topic 505](https://www.irs.gov/taxtopics/tc505))

HELOC vs Cash-Out Refinance vs Personal Loan

The right choice depends on three factors: your current mortgage rate, the amount you need to borrow, and whether you can tolerate a variable rate. A HELOC preserves your existing mortgage and charges interest only on the amount you draw. A cash-out refinance replaces your mortgage with a larger loan at today's rates — a loss if your current rate is below market. A personal loan is unsecured and carries no foreclosure risk, but rates run 2 to 4 times higher than HELOC rates.

The breakeven point is usually around $50,000 of borrowing need and a 5-year horizon. Below that, a personal loan is often cheaper after accounting for fees and the variable-rate risk of a HELOC. Above $75,000, the HELOC's lower rate and larger limit win. Between the two, run both scenarios before committing.

When a HELOC Is the Wrong Choice

Three situations where HELOC loses. First, if you cannot comfortably handle the payment shock at the end of the draw period — the jump from interest-only to amortizing can be 20% to 35%. Second, if you do not have stable income for the full draw plus repayment timeline. Third, if you would be borrowing against home equity to cover recurring expenses rather than a one-time need. Borrowing against your home to fund a lifestyle gap is the fastest path to foreclosure.

The rule of thumb: use a HELOC for a specific, closed-ended purpose. Use it for a kitchen remodel, a medical event, or a business investment with a clear payback. Do not use it for credit card debt that keeps recurring, ongoing monthly shortfalls, or speculative investments. If you cannot name the purpose in one sentence, do not borrow against the house.