You can use a line of credit for a down payment, but only if that line is secured by a real asset such as a home equity line of credit on another property or a margin loan against an investment portfolio. Unsecured personal lines of credit, credit card cash advances, and signature loans are flatly barred by both Fannie Mae and FHA guidelines. That single distinction — secured versus unsecured — decides whether underwriting approves your file or sends it back.
Which Lines of Credit Qualify
Fannie Mae’s Selling Guide is explicit. Section B3-4.3-15 accepts borrowed funds as a source for the down payment, closing costs, and reserves when the loan is secured by an asset with enough documented value to support the debt.1Fannie Mae. Borrowed Funds Secured by an Asset A HELOC or second mortgage on a property you already own qualifies. So does a loan against an investment account or similar collateral.
Section B3-4.3-17 lists what does not qualify: signature loans, credit card lines of credit, and even overdraft protection on checking accounts.2Fannie Mae. Personal Unsecured Loans The reasoning is that unsecured debt gives the lender no fallback if you default across the board.
FHA follows the same principle. HUD allows a borrower to obtain a loan for the full required investment as long as the loan is fully secured by assets like investment accounts or real property other than the home being purchased. Unsecured signature loans, credit card advances, and borrowing against household goods are unacceptable. FHA also requires that borrowed funds come from an independent third party, so the seller, real estate agent, or lender cannot be the source.3HUD. HUD 4155.1 Chapter 5, Section B – Acceptable Sources of Borrower Funds
The Debt-to-Income Problem
Qualifying the source is only half the fight. The monthly payment on your new line of credit becomes a debt the lender counts against you. Your debt-to-income ratio adds up all monthly obligations — car loans, student loans, credit card minimums, the new HELOC payment, and the proposed mortgage — and divides by gross monthly income.
Fannie Mae’s caps depend on how the loan is underwritten. Manually underwritten loans max out at 36% DTI, or 45% if the borrower clears additional credit score and reserve thresholds. Loans run through Desktop Underwriter allow up to 50% DTI.4Fannie Mae. Debt-to-Income Ratios
Consider the arithmetic. Suppose your gross monthly income is $10,000 and your existing debts total $2,000 per month, putting you at 20% DTI. You draw $60,000 from a HELOC with a minimum monthly payment of $450. Your non-mortgage debt is now $2,450. Add a proposed mortgage payment of $2,800 and your DTI lands at 52.5%, which is past even the automated cap. The lender either shrinks your mortgage or declines the file. Run these numbers before you draw on any line.
Combined Loan-to-Value Ceilings
When you borrow against one property to fund a down payment on another, the new home still faces a combined loan-to-value ceiling that stacks the first mortgage with any subordinate financing. Fannie Mae’s eligibility matrix caps CLTV at 97% for a single-unit primary residence with a fixed-rate mortgage, 95% for adjustable-rate, 90% for a single-unit second home, and 85% for a single-unit investment property.5Fannie Mae. Eligibility Matrix
Subordinate financing recorded against the property being purchased is allowed on primary residences up to a 90% CLTV, and can reach 105% under Fannie Mae’s Community Seconds program. The subordinate lien must be recorded, evidenced by a promissory note, clearly subordinate to the first mortgage, and fully amortizing with a maturity date at least five years after the first mortgage’s note date.6Fannie Mae. Subordinate Financing Borrowers who put in very little of their own cash tend to hit these caps quickly.
Seasoning and Large Deposits
Timing matters as much as source. Lenders review at least two months of bank statements and flag anything unusual. Funds that have sat in your account before the statement period the lender reviews are considered seasoned; the working threshold is 60 days.7Fannie Mae. Depository Accounts
Fannie Mae defines a large deposit as any single deposit exceeding 50% of your total monthly qualifying income. If you earn $8,000 per month in qualifying income and deposit $4,500 from a HELOC draw, that triggers the sourcing process. Only the unsourced portion of a deposit counts, so a partially documented deposit is measured by its unexplained piece alone.
If you plan to fund your down payment with a HELOC or other secured line, draw and deposit the funds well before you apply for the mortgage. Seasoning won’t eliminate disclosure of the underlying debt, but it reduces back-and-forth over the deposit itself.
Documentation Your Lender Will Require
Underwriters are trained to be skeptical of down payment sourcing. Come in with a complete paper trail:
- Two months of statements for the line of credit showing balance, draws, and payment history.
- The original credit agreement showing interest rate, credit limit, and how minimum payments are calculated.
- A letter of explanation describing why you borrowed the funds, the amount, and how the money relates to the home purchase, referencing your loan application number and any attached documents.
- Two months of bank statements for the account where the funds landed, showing the deposit and current balance.
The line of credit must be current with no delinquent history. Late payments on the credit line can lead to a denial, not because of the missed payment alone but because it reads as cash-flow stress at the exact moment you’re taking on a major new obligation.
The Pre-Closing Check
Approval is not the finish line. Lenders pull a final verification of credit and liabilities shortly before closing. If new subordinate financing is discovered or disclosed after underwriting but before closing, Fannie Mae requires the lender to re-underwrite the loan.8Fannie Mae. Selling Guide March 4, 2026 If the recalculated DTI exceeds 50% for a DU loan or 45% for a manually underwritten loan, the loan becomes ineligible for delivery to Fannie Mae.4Fannie Mae. Debt-to-Income Ratios
All liabilities must be accurately reflected on the Uniform Residential Loan Application, Form 1003.9Fannie Mae. Uniform Residential Loan Application (Form 1003) Some borrowers assume they can draw on a line of credit between approval and closing without consequence. That assumption is wrong. The pre-closing check exists to catch exactly that, and getting flagged at that stage can delay or kill the deal.
Why Full Disclosure Matters
Hiding a line of credit from your lender is not only a risk to your approval. Making false statements on a federally related mortgage application is a federal crime under 18 U.S.C. § 1014, carrying penalties of up to $1,000,000 in fines, up to 30 years in prison, or both.10Office of the Law Revision Counsel. 18 U.S. Code 1014 Those are statutory maximums rather than typical sentences, but the exposure is real, and omitting a debt that changes your qualification picture is the type of conduct the statute targets.
Lenders also use undisclosed-debt monitoring that flags new credit inquiries and account openings between application and closing. Even an unintentional omission — an old line of credit you forgot about — creates friction that delays the purchase and erodes lender trust.
Tax Treatment When the HELOC Funds Move to a Different Property
If you tap a HELOC on your current home to fund a down payment on a new one, the interest deduction rules may catch you off guard. Under current IRS guidance, interest on a home equity loan or line of credit is deductible only when the funds are used to buy, build, or substantially improve the home that secures the loan.11Internal Revenue Service. Publication 936, Home Mortgage Interest Deduction
A HELOC on Property A used for a down payment on Property B produces interest that is generally not deductible as home mortgage interest, because the borrowed funds did not improve the property securing the loan. The combined acquisition debt limit for deductible mortgage interest remains $750,000 for loans taken after December 15, 2017, or $375,000 for married filing separately. This doesn’t make the strategy wrong, but it changes the after-tax cost. Borrowing at 7% on a $60,000 HELOC draw with no deduction is $4,200 a year in fully after-tax cost, and that number should be weighed against alternatives like liquidating investments or paying private mortgage insurance.
Business Lines of Credit and Retirement Loans
Self-employed borrowers sometimes look at a business line of credit. Fannie Mae allows business assets as an acceptable source for down payment, closing costs, and reserves if the borrower is listed as an owner of the account, and the lender must investigate any indication that the funds were borrowed rather than accumulated through operations. Expect to provide business bank statements, tax returns, and possibly a CPA letter confirming the withdrawal won’t impair the business.
A 401(k) loan is a separate route. Fannie Mae treats vested funds in tax-favored retirement accounts as acceptable, provided the lender verifies ownership and confirms the account allows withdrawals.12Fannie Mae. Retirement Accounts A 401(k) loan doesn’t show up as traditional debt on your credit report, but the repayment obligation still affects your DTI, and leaving your employer while the balance is outstanding creates repayment risk.