Is Securities-Based Line of Credit Interest Tax Deductible?

Interest on a securities-based line of credit is tax deductible only when you spend the borrowed money on something the tax code favors — an investment held for income, a business you actively run, or in some cases a qualifying home purchase. The brokerage account you pledged as collateral has nothing to do with it. The IRS classifies interest by where the cash goes, not by what secures the loan, so the same SBLOC can produce a full deduction, a limited deduction, or none at all depending on the check you wrote with the proceeds.

Where the Money Goes Decides Everything

The IRS uses “tracing rules” to follow SBLOC cash from your lender to whatever you ultimately buy or pay for. That final use puts the interest into a category, and the category sets the rule.¹

Three categories cover most SBLOC borrowers:

Investment interest, when you use the proceeds to acquire or carry property held for investment — rental land, precious metals, or other non-securities investment assets. Deductible up to your net investment income for the year.²
Business interest, when you use the proceeds in a trade or business you materially participate in, such as a sole proprietorship, partnership, or S corporation you actively run. Deductible, subject to a separate cap tied to business income.²
Personal interest, when you use the proceeds for tuition, a vacation, a personal car, or general living expenses. Not deductible.²

Two less common categories can also apply. If the proceeds go into a rental property or a business you do not materially participate in, the interest is passive activity interest and is deductible only against passive income.³ If the proceeds buy, build, or substantially improve your primary or secondary home, the interest may qualify as deductible residence interest, subject to the $750,000 acquisition debt limit ($375,000 if married filing separately).⁴

Pledging investment assets does not convert personal spending into investment spending. The collateral is irrelevant.

Investment Interest and the Net Investment Income Cap

When SBLOC interest qualifies as investment interest, the deduction is capped at your net investment income (NII) for the year. NII is your investment income minus your investment expenses, without counting the interest itself.²

Investment income for this purpose generally includes taxable interest, non-qualified dividends, royalties, and short-term capital gains. Qualified dividends and long-term capital gains are excluded by default because they already receive preferential tax rates. On the expense side, the permanent elimination of miscellaneous itemized deductions means advisory and custodial fees no longer reduce NII for most taxpayers.⁵

Electing to Include Qualified Dividends and LTCG

If your investment interest exceeds NII, you can elect on Form 4952, line 4g to pull some or all of your qualified dividends and long-term capital gains into NII. The catch: every dollar you reclassify loses its preferential 0%, 15%, or 20% rate and gets taxed as ordinary income.¹

The election pays off only when the tax savings from the added interest deduction beat the extra tax on the reclassified income. In the 37% bracket with substantial interest and thin ordinary investment income, the math sometimes works. For most borrowers it deserves a calculation, not a reflex.

Carryforward of Excess

Any investment interest disallowed by the NII cap carries forward indefinitely and gets added to next year’s investment interest expense, subject again to that year’s NII cap.⁶ So if you pay $40,000 in SBLOC interest on funds used to buy investment real estate but your NII is only $30,000, you deduct $30,000 this year and roll the remaining $10,000 into next year’s calculation.

Business Interest and the 163(j) Limit

SBLOC proceeds put into a business you materially participate in produce business interest. The deduction is capped at your business interest income plus 30% of adjusted taxable income (ATI) from that business.²

Since 2022, ATI has been calculated on an EBIT basis, meaning depreciation and amortization are no longer added back. That makes the cap tighter, especially for capital-intensive businesses. Excess business interest carries forward under its own set of rules.

Small businesses escape the cap entirely if their average annual gross receipts over the prior three years fall below the inflation-adjusted threshold, $32 million for 2026. Meet that test and the full amount of business interest is deductible without the 30% ceiling.

When SBLOC Interest Produces No Deduction

Personal use is the common trap. Draw on the line to pay tuition, buy a personal-use car, take a trip, or cover household expenses, and the interest is personal interest with zero tax benefit.²

Tax-exempt investments are the less obvious trap. Use SBLOC proceeds to buy municipal bonds or other federally tax-exempt obligations and the interest expense allocable to those holdings is non-deductible. You cannot deduct borrowing costs used to generate tax-free income.⁷

A narrower rule catches straddle positions. If SBLOC proceeds fund offsetting positions in personal property, such as certain options strategies, the interest and carrying charges must be capitalized into the position’s cost basis rather than deducted currently.⁸

Tracing the Money in Practice

The 30-Day Window

You do not have to spend SBLOC proceeds the moment they hit your account. IRS guidance treats any expenditure made from any of your accounts, or from cash, within 30 days before or 30 days after the SBLOC deposit as being made from those proceeds.¹ You can line up the purchase first and draw after, or draw first and close within a month, without breaking the classification.

Mixed Uses and Repayment Order

A single draw split across purposes gets its interest allocated proportionally. Borrow $100,000, put $80,000 into investment property and $20,000 into personal spending, and 80% of the interest is investment interest while 20% is non-deductible personal interest.¹

When you pay down a mixed-use balance, the IRS applies payments to the personal-use portion first. The non-deductible share shrinks ahead of the deductible one, which improves the deductible percentage of the remaining balance over time.¹

Records the IRS Expects

Commingling SBLOC proceeds with personal or business funds in one account makes tracing hard to prove on audit. The clean approach is a dedicated account for SBLOC proceeds with purchases made directly from it. Keep loan statements showing interest and balances, deposit records tying the SBLOC draw to that account, and purchase documentation linking each disbursement to the specific asset or expense.⁹

The NIIT Angle for High Earners

Investment interest that clears the regular NII cap also reduces your exposure to the 3.8% Net Investment Income Tax. The NIIT applies to individuals with modified adjusted gross income above $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately), and those thresholds are not indexed for inflation.

The deduction flows onto Form 8960, line 9a, and reduces net investment income for NIIT purposes. Only the amount actually allowed counts; a portion disallowed under the regular NII cap does not reduce the NIIT base until the year it is finally deducted through the carryforward.¹⁰¹¹

The result for high-income borrowers is a double benefit. At a 37% ordinary rate combined with the 3.8% NIIT, the marginal value of the deduction can exceed 40 cents per dollar of interest paid.

Do Not Pledge an IRA

Using an IRA as collateral for any loan, an SBLOC included, is a prohibited transaction. The consequence is severe: the entire IRA is treated as distributed on the first day of the year the violation occurs, the full fair market value becomes taxable, and an additional early distribution penalty may apply if you are under 59½.¹² Most brokers will not let you do it, but the penalty is disproportionate enough to the mistake that it belongs on any borrower’s radar. Only taxable brokerage assets should secure an SBLOC.

How to Report It on Your Return

Investment Interest — Form 4952

Investment interest is calculated on Form 4952, which reconciles total investment interest paid against NII and computes any carryforward. The deductible amount from line 8 flows to Schedule A (Form 1040), line 9.⁶

Because it is an itemized deduction, it only helps if your total itemized deductions exceed the standard deduction. For 2026 the standard deduction is $16,100 for single filers, $32,200 for joint filers, and $24,150 for heads of household.⁵ Most SBLOC borrowers with sizable portfolios clear that with mortgage interest, state and local taxes, and the investment interest itself, but check before assuming the deduction has value.

Business and Passive Activity Interest

Business interest does not go through Form 4952 or Schedule A. Report it on Schedule C for a sole proprietorship or Schedule E for partnerships and S corporations. Passive activity interest also goes on Schedule E and is limited to passive income from the same or other passive activities.²

AMT

Investment interest stays deductible under the Alternative Minimum Tax, but the calculation uses AMT-adjusted figures on a separate Form 4952. The difference between the regular and AMT amounts is reported on Form 6251.¹³

1
Internal Revenue Service. Publication 550 (2025), Investment Income and Expenses
2
Office of the Law Revision Counsel. 26 USC 163 – Interest
3
Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited
4
Internal Revenue Service. Real Estate (Taxes, Mortgage Interest, Points, Other Property Expenses)
5
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
6
Internal Revenue Service. Form 4952, Investment Interest Expense Deduction
7
Office of the Law Revision Counsel. 26 USC 265 – Expenses and Interest Relating to Tax-Exempt Income
8
Office of the Law Revision Counsel. 26 USC 263 – Capital Expenditures
9
eCFR. 26 CFR 1.163-8T – Allocation of Interest Expense Among Expenditures (Temporary)
10
eCFR. 26 CFR 1.1411-4 – Definition of Net Investment Income
11
Internal Revenue Service. 2025 Instructions for Form 8960 – Net Investment Income Tax
12
Internal Revenue Service. Retirement Topics – Prohibited Transactions
13
Internal Revenue Service. Instructions for Form 6251 (2025)