Can I deduct the interest paid on a personal loan I took out to purchase stocks or mutual funds in 2025?

The deductibility of interest paid on loans used to purchase or carry investments, such as stocks, bonds, or mutual funds, depends heavily on how the loan is structured and the nature of the underlying investment. For the 2025 tax year, the rules governing investment interest expense are precise.

### Investment Interest Expense (IIE)

Interest paid on a loan used to purchase or carry property held for investment is classified as Investment Interest Expense (IIE). This includes margin loan interest from a brokerage account or interest paid on a non-purpose loan (a personal loan not secured by investment property, but where the proceeds were used to buy investments).

Deductibility Limit: The deduction for IIE in any given year is limited to the amount of your net investment income (NII) for that year. You cannot deduct IIE that exceeds your NII.

Net Investment Income (NII) Components: NII includes:

• Interest, dividends, annuities, and royalties from property held for investment.
• Net short-term capital gains from the sale of investment property.
• It generally excludes income that is already tax-exempt (like municipal bond interest) or income derived from a trade or business (like active trading business income).

Reporting: Investment interest expense is reported on Form 4952, Investment Interest Expense Deduction.

### Distinction: Margin Loans vs. Personal Loans

• Margin Loans: Interest on margin loans from a broker is almost always treated as IIE because the loan is secured by the investment property in the account.
• Personal Loans (Non-Purpose Loans): If you take out a standard personal loan or home equity loan and use the funds to buy stocks, the interest may be deductible as IIE, provided the IRS can trace the use of the funds to investment purposes. If the loan is secured by your primary residence and the funds are used for investment, the interest might be subject to different rules, but generally, if used for investment, it falls under the IIE rules.

### What is NOT Deductible?

It is vital to distinguish investment interest expense from other types of interest that are non-deductible:

• Personal Interest: Interest on credit cards, car loans (unless used 100% for business), and personal lines of credit is generally not deductible.
• Home Mortgage Interest: Interest on a primary residence mortgage is only deductible up to certain debt limits and must be itemized.

### Carryover of Disallowed Interest

If your calculated IIE exceeds your NII in 2025, the excess amount is not lost. It is carried forward indefinitely to the next tax year, where it can be deducted, subject to the NII limit of that subsequent year.

Taxpayers must meticulously track their investment expenses and income to correctly calculate NII and apply the limitations on Form 4952. If the investment activity rises to the level of a trade or business (e.g., professional day trading), the rules shift, and expenses might be treated differently under Section 162.