The tax treatment of accrued interest turns on two things: the accounting method you use and the kind of debt instrument that produced the interest. Cash-method taxpayers generally report interest when they receive it and deduct interest when they pay it. Accrual-method taxpayers report it as it’s earned and deduct it as it’s incurred. And a handful of instruments, most famously zero-coupon bonds, override both methods and force you to pay tax each year on interest that’s still locked inside the investment. Getting these rules straight matters, because the IRS receives a copy of every 1099 and its matching program is unforgiving.
When Accrued Interest Becomes Taxable
Your accounting method sets the timing. Most individuals and smaller businesses use the cash method: interest income is taxable when it hits your account, and interest expense is deductible when you actually pay it.
Under the accrual method, income is taxable once your right to receive it is fixed and the amount can be determined with reasonable accuracy, whether or not cash has changed hands. Expenses are deductible once the liability is established and economic performance has occurred. For interest on a loan, economic performance happens as time passes, so an accrual-basis business deducts interest continuously over the loan term rather than waiting for the check to clear.
Cash-method taxpayers also have to reckon with constructive receipt. Interest is taxable when it’s credited to your account or otherwise made available to you, even if you don’t withdraw it. If a bank credits interest to your savings account on December 31, that interest belongs on that year’s return, even if the money sits untouched until March. Restrictions like minimum withdrawal amounts or advance notice periods don’t change the result.1eCFR. 26 CFR 1.451-2 – Constructive Receipt of Income
Original Issue Discount and Phantom Income
Original issue discount is where accrued interest most often catches people off guard. OID arises when a debt instrument is issued for less than its face value at maturity. The gap between what you paid and what you’ll eventually receive is treated as interest that accrues over the life of the instrument, and federal law requires you to include a portion in your gross income every year using a constant yield method.2Internal Revenue Service. Publication 1212 – Guide to Original Issue Discount (OID) Instruments This applies regardless of whether you use the cash or accrual method.3eCFR. 26 CFR 1.1272-1 – Current Inclusion of OID in Income
The classic example is a zero-coupon bond. You buy it at a discount, receive no interest along the way, and collect the full face value at maturity. Even though you never see a dime of interest until the bond matures, you owe tax each year on the OID that accrued. This is often called phantom income, because you’re taxed on money that hasn’t reached you yet. The rules also apply to certain corporate bonds, Treasury STRIPS, and other long-term instruments where the stated coupon is below the instrument’s true yield. Your broker or the issuer sends Form 1099-OID each year showing the amount you must include.4Internal Revenue Service. About Form 1099-OID
Not every discounted bond triggers annual OID reporting. If the total OID is less than one-quarter of one percent (0.25%) of the stated redemption price at maturity, multiplied by the number of complete years to maturity, the OID is treated as zero.5Office of the Law Revision Counsel. 26 USC 1273 – Determination of Amount of Original Issue Discount Bonds below that threshold produce capital gain, not annual income, when sold or redeemed.
Because you receive no cash from a zero-coupon bond, set aside enough elsewhere to cover the annual tax. Investors who assume that nothing was received means nothing is owed are exactly the ones the matching program flags.
Market Discount Bonds
Market discount is a different animal. It arises when you buy a bond on the secondary market for less than its face value (or, for an OID bond, less than its adjusted issue price). Unlike OID, market discount isn’t taxed year by year. When you sell or redeem the bond, any gain is treated as ordinary interest income up to the amount of accrued market discount.6Office of the Law Revision Counsel. 26 USC 1276 – Disposition Gain Representing Accrued Market Discount Treated as Ordinary Income That matters because ordinary income is taxed at your full marginal rate, while long-term capital gains get preferential rates.
A de minimis rule applies here too. If the market discount is less than 0.25% of the stated redemption price at maturity, multiplied by the number of complete years remaining after you buy the bond, the discount is treated as zero and any gain on disposition is capital gain rather than ordinary income.7Office of the Law Revision Counsel. 26 USC 1278 – Definitions and Special Rules for Market Discount
You can also elect to include market discount in income currently as it accrues rather than waiting for disposition. Once made, the election applies to all market discount bonds you acquire that year and afterward. The main reason to elect in is to avoid a large ordinary-income hit in the year of sale.
Buying a Bond Between Interest Payments
When you buy a bond between coupon dates, you pay the seller accrued interest on top of the purchase price. That amount is taxable to the seller, not to you. But when the next coupon arrives, you receive the full payment and your broker reports the whole thing on Form 1099-INT, including the piece you already reimbursed the seller.8Internal Revenue Service. Instructions for Schedule B (Form 1040)
To avoid paying tax on interest that was really a return of your purchase price, report the full 1099-INT amount on Schedule B, then subtract the accrued interest you paid at purchase as a separate line labeled “Accrued Interest.” The subtotal on line 2 reflects only the interest you actually earned. Skipping this adjustment is one of the more common mistakes bond investors make.
Tax-Exempt Bonds Work Differently
Tax-exempt municipal bonds are generally excluded from the annual OID inclusion rules, so you don’t report OID on them as income each year. The OID still affects your cost basis, though. You increase your basis by the amount of OID that would have been includable had the bond been taxable, and that adjusted basis determines your gain or loss when you sell.2Internal Revenue Service. Publication 1212 – Guide to Original Issue Discount (OID) Instruments
For stripped tax-exempt bonds or stripped coupons acquired after October 22, 1986, the OID remains nontaxable, but you must accrue it for basis purposes at disposition. If the bond is a covered security under broker reporting rules, your brokerage will make this adjustment automatically and report the adjusted basis on Form 1099-B.
Deducting Interest You’ve Paid
On the borrower’s side, whether accrued interest is deductible depends on what the money was used for. Not every kind of interest gets a deduction.
Personal Interest
Interest on credit cards, car loans, and other personal debt is not deductible. The tax code disallows any deduction for personal interest, defined as any interest that doesn’t fall into one of the specific carved-out categories: trade or business interest, investment interest, passive activity interest, qualified home mortgage interest, certain estate tax interest, and student loan interest.9Office of the Law Revision Counsel. 26 USC 163 – Interest – Section (h) If your interest doesn’t fit one of those buckets, the deduction is zero.
Investment Interest
Interest on money borrowed to buy or hold investments (stocks, bonds, land held for appreciation) is deductible, but only up to your net investment income for the year.10Office of the Law Revision Counsel. 26 USC 163 – Interest – Section (d) Net investment income is generally your gross income from investment property (interest, ordinary dividends, royalties) minus investment expenses other than interest. Qualified dividends and long-term capital gains are excluded by default. You can elect to include them, but the price is losing their preferential tax rates on the included amount.11Internal Revenue Service. Publication 550 (2025) – Investment Income and Expenses
Any investment interest that exceeds net investment income isn’t lost. The disallowed portion carries forward indefinitely and is treated as investment interest paid in the next year, until you have enough net investment income to absorb it. You calculate the deduction on Form 4952.12Internal Revenue Service. About Form 4952, Investment Interest Expense Deduction
Business Interest
Business interest is generally deductible, but larger businesses face a cap under Section 163(j): the deduction can’t exceed the sum of the business’s interest income, 30% of its adjusted taxable income, and any floor plan financing interest.13Office of the Law Revision Counsel. 26 USC 163 – Interest – Section (j) Amounts disallowed under this rule carry forward. A small business exemption removes the cap entirely for taxpayers whose average annual gross receipts over the prior three years fall under the Section 448(c) threshold, which is $31 million for tax years beginning in 2025.14Internal Revenue Service. Internal Revenue Bulletin 2024-45
Forms You’ll Need
Several forms come into play, and matching the right form to the right situation is where a lot of returns go wrong.
- Form 1099-INT reports taxable interest income of $10 or more from banks, brokerages, and other payers.15Internal Revenue Service. About Form 1099-INT, Interest Income
- Form 1099-OID reports the annual OID accrual you must include even if no cash was paid. If a bond has both qualified stated interest and OID, the payer may report everything on 1099-OID rather than issuing both forms.16Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID
- Schedule B is where you list interest income and, when applicable, subtract accrued interest paid to a bond seller.
- Form 4952 calculates the investment interest deduction and tracks any carryforward. An exception lets you skip it if your interest and ordinary dividend income exceed your investment interest expense, you have no other investment expenses, and you have no carryforward from the prior year.17Internal Revenue Service. Form 4952 – Investment Interest Expense Deduction
If you buy or sell a bond mid-year, reconcile the 1099 amounts against your own records. The 1099 may show a full year’s interest or OID even though you only held the bond for part of the year, and the allocation is on you to get right.
What Happens If You Don’t Report It
Missing OID or other accrued interest that shows up on a 1099 is one of the fastest ways to draw an IRS notice. The IRS specifically treats failure to include income shown on an information return as a sign of negligence, and the accuracy-related penalty for negligence is 20% of the resulting underpayment.18Internal Revenue Service. Accuracy-Related Penalty
A harsher version of the same penalty applies to substantial understatements, meaning the tax on your return is understated by the greater of 10% of the correct tax or $5,000. The rate stays 20%, but it applies to a larger base. Interest runs on both the unpaid tax and the penalty, so the cost grows the longer the balance sits.
The phantom-income nature of OID makes this a particularly common trap. Investors who receive no cash from a zero-coupon bond sometimes assume there’s nothing to report, but the IRS has its own copy of every 1099-OID. If you hold OID instruments, plan for the tax bill even in years when the investment pays you nothing.