Investment Interest: Investment Taxes (2025 IRS Guide)
This guide covers “Investment Interest” within investment taxes. The following material presents the IRS treatment of this topic, including the qualifications, exceptions, and examples in the source section. Read the rules alongside the facts of your own situation before deciding what to report, deduct, or document.
Adapted from Publication 550 (2025), Investment Income and Expenses, published by the Internal Revenue Service. This guide retains the source edition’s years, amounts, deadlines, and examples. It is guidance for that edition, not a statement that the same figures apply to every tax year.
Context for these rules
This section discusses interest expenses you may be able to deduct as an investor.
For information on business interest, see chapter 8 of Pub. 334, Tax Guide for Small Business.
You generally cannot deduct personal interest. However, you can deduct qualified home mortgage interest, as explained in Pub. 936, Home Mortgage Interest Deduction. You may be able to deduct interest on certain student loans. See Pub. 970, Tax Benefits for Education.
Investment Interest
If you borrow money to buy property you hold for investment, the interest you pay is investment interest. You can deduct investment interest subject to the limit discussed later. However, you cannot deduct interest you incurred to produce tax-exempt income. See Tax-exempt income, later. You also cannot deduct interest expenses on straddles discussed under Interest expense and carrying charges on straddles, later.
Investment interest does not include any qualified home mortgage interest or any interest taken into account in computing income or loss from a passive activity.
Investment property.
Property held for investment includes property that produces interest, dividends, annuities, or royalties not derived in the ordinary course of a trade or business. It also includes property that produces gain or loss (not derived in the ordinary course of a trade or business) from the sale or trade of property producing these types of income or held for investment (other than an interest in a passive activity). Investment property also includes an interest in a trade or business activity in which you did not materially participate (other than a passive activity).
Partners, shareholders, and beneficiaries.
To determine your investment interest, combine your share of investment interest from a partnership, S corporation, estate, or trust with your other investment interest.
Allocation of Interest Expense
If you borrow money for business, personal purposes, or investment, you must allocate the debt among those purposes. Only the interest expense on the part of the debt used for investment purposes is treated as investment expense. The allocation is not affected by the use of property that secures the debt.
Example 1.
You borrow $10,000 and use $8,000 to buy stock. You use the other $2,000 to buy items for your home. Because 80% of the debt is used for, and allocated to, investment purposes, 80% of the interest on that debt is investment interest. The other 20% is nondeductible personal interest.
Debt proceeds received in cash.
If you receive debt proceeds in cash, the proceeds are generally not treated as investment property.
Debt proceeds deposited in account.
If you deposit debt proceeds in an account, that deposit is treated as investment property, regardless of whether the account bears interest. But, if you withdraw the funds and use them for another purpose, you must reallocate the debt to determine the amount considered to be for investment purposes.
Example 2.
Assume in Example 1 that you borrowed the money on March 1 and immediately bought the stock for $8,000. You did not buy the household items until June 1. You had deposited the $2,000 in the bank. You had no other transactions on the bank account until June. You did not sell the stock, and you made no principal payments on the debt. You paid interest from another account. The $8,000 is treated as being used for an investment purpose. The $2,000 is treated as being used for an investment purpose for the 3-month period. Your total interest expense for 3 months on this debt is investment interest. In June, when you spend the $2,000 for household items, you must begin to allocate 80% of the debt and the interest expense to investment purposes and 20% to personal purposes.
Amounts paid within 30 days.
If you receive loan proceeds in cash or if the loan proceeds are deposited in an account, you can treat any payment (up to the amount of the proceeds) made from any account you own, or from cash, as made from those proceeds. This applies to any payment made within 30 days before or after the proceeds are received in cash or deposited in your account.
If you received the loan proceeds in cash, you can treat the payment as made on the date you received the cash instead of the date you actually made the payment.
Payments on debt may require new allocation.
As you repay a debt used for more than one purpose, you must reallocate the balance. You must first reduce the amount allocated to personal purposes by the repayment. You then reallocate the rest of the debt to find what part is for investment purposes.
Example 3.
If, in Example 2, you repay $500 on November 1, the entire repayment is applied against the amount allocated to personal purposes. The debt balance is now allocated as $8,000 for investment purposes and $1,500 for personal purposes. Until the next reallocation is necessary, 84% ($8,000 ÷ $9,500) of the debt and the interest expense is allocated to investment.
Pass-through entities.
If you use borrowed funds to buy an interest in a partnership or S corporation, then the interest on those funds must be allocated based on the assets of the entity. If you contribute to the capital of the entity, you can make the allocation using any reasonable method.
Additional allocation rules.
For more information about allocating interest expense, see chapter 8 of Pub. 334.
When To Deduct Investment Interest
If you use the cash method of accounting, you must pay the interest expense before you can deduct it.
If you use an accrual method of accounting, you can deduct interest over the period it accrues, regardless of when you pay it. For an exception, see Unpaid expenses owed to related party, later in this chapter.
Example.
You borrowed $1,000 on August 19, 2025, payable in 90 days at 4% interest. On November 18, 2025, you paid this with a new note for $1,010, due on February 17, 2026. If you use the cash method of accounting, you cannot deduct any part of the $10 interest on your return for 2025 because you did not actually pay it in that year. If you use an accrual method, you may be able to deduct a portion of the interest on the loans through December 31, 2025, on your return for 2025.
Interest paid in advance.
Generally, if you pay interest in advance for a period that goes beyond the end of the tax year, you must spread the interest over the tax years to which it belongs under the OID rules discussed in chapter 1. You can deduct in each year only the interest for that year.
Interest on margin accounts.
If you are a cash method taxpayer, you can deduct interest on margin accounts to buy taxable securities as investment interest in the year you paid it. You are considered to have paid interest on these accounts only when you actually pay the broker or when payment becomes available to the broker through your account. Payment may become available to the broker through your account when the broker collects dividends or interest for your account, or sells securities held for you or received from you.
Limit on interest deduction for market discount bonds.
The amount you can deduct for interest expense you paid or accrued during the year to buy or carry a market discount bond may be limited. This limit does not apply if you accrue the market discount and include it in your income currently.
Under this limit, the interest is deductible only to the extent it is more than:
-
The total interest and OID includible in gross income for the bond for the year, plus
-
The market discount for the number of days you held the bond during the year.
Interest not deducted due to limit.
In the year you dispose of the bond, you can deduct any interest expense you were not allowed to deduct in earlier years because of the limit.
Choosing to deduct disallowed interest expense before the year of disposition.
You can choose to deduct disallowed interest expense in any year before the year you dispose of the bond, up to your net interest income from the bond during the year. The rest of the disallowed interest expense remains deductible in the year you dispose of the bond.
Net interest income.
This is the interest income (including OID) from the bond that you include in income for the year, minus the interest expense paid or accrued during the year to purchase or carry the bond.
Limit on interest deduction for short-term obligations.
If the current income inclusion rules discussed in chapter 1 under Discount on Short-Term Obligations do not apply to you, the amount you can deduct for interest expense you paid or accrued during the year to buy or carry a short-term obligation is limited.
The interest is deductible only to the extent it is more than:
-
The amount of acquisition discount or OID on the obligation for the tax year, plus
-
The amount of any interest payable on the obligation for the year that is not included in income because of your accounting method (other than interest taken into account in determining the amount of acquisition discount or OID).
Interest not deducted due to limit.
In the year you dispose of the obligation, or, if you choose, in another year in which you have net interest income from the obligation, you can deduct any interest expense you were not allowed to deduct for an earlier year because of the limit. Follow the same rules provided in the earlier discussion under Limit on interest deduction for market discount bonds.
Using the guidance
Keep the documents that establish the dates, amounts, and circumstances described above. References to other chapters, forms, worksheets, or earlier and later sections refer to the linked IRS publication. Check the full publication and its updates before relying on a rule for a different tax year or a situation not addressed here.
Sources and further reading
- Publication 550 (2025), Investment Income and Expenses: Investment Expenses — Interest Expenses — Investment Interest — Internal Revenue Service; 2025 edition.
The cited U.S. government text is in the public domain. Source accessed October 28, 2026. Fynoptic has organized this material for educational use and is independent of, and not endorsed by, the IRS.