The difference between interest income and capital gains tax comes down to two things: when you owe the tax and what rate applies. Interest income is taxed every year at your ordinary income rate, the same schedule that applies to your wages. Capital gains are only taxed when you sell, and if you held the asset more than a year, you get preferential rates that top out at 20% instead of 37%. That gap is the reason the distinction matters on your return.
What Each Type of Income Actually Is
Interest is what someone pays you for the use of your money. Savings accounts, CDs, corporate bonds, and Treasury securities all generate interest, and federal law includes it directly in gross income.1Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined It arrives on a schedule whether you do anything or not. A savings account credits it monthly. A bond pays it semiannually. You owe tax on it in the year you earn it.
A capital gain is the profit from selling a capital asset for more than you paid. The tax code defines a capital asset broadly to cover most property you hold for personal or investment purposes.2Office of the Law Revision Counsel. 26 US Code 1221 – Capital Asset Defined Stocks, real estate, collectibles, and cryptocurrency all qualify. Nothing is owed until the sale happens. A stock could triple in value and you owe zero until the day you close the trade.
The holding period then decides which rate applies. Assets held one year or less produce short-term gains. Assets held more than one year produce long-term gains.3Office of the Law Revision Counsel. 26 US Code 1222 – Other Terms Relating to Capital Gains and Losses That one-year line is where the tax math starts to diverge sharply from interest.
How the Rates Compare
Interest income is always taxed at ordinary income rates, which for 2026 run from 10% to 37%.4Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Short-term capital gains use those same rates, so a stock you flip after three months is taxed like the interest from your savings account.
Long-term capital gains get their own, lower schedule. For 2026:
- 0% on taxable income up to $49,450 (single), $98,900 (married filing jointly), or $66,200 (head of household)
- 15% on income from those thresholds up to $545,500 (single), $613,700 (married filing jointly), or $579,600 (head of household)
- 20% on income above those amounts
The practical impact is large.5Tax Foundation. 2026 Tax Brackets and Federal Income Tax Rates A single filer with $200,000 in taxable income pays a 32% marginal rate on interest but only 15% on a long-term gain. On a $10,000 return, that is $3,200 versus $1,500 in federal tax. The gap widens as income rises and narrows at lower brackets, but at nearly every income level, long-term capital gains carry a lighter load than interest.
The 3.8% Net Investment Income Tax
Higher earners pay an extra 3.8% surtax on net investment income, and both interest and capital gains count toward it. It applies when modified adjusted gross income exceeds $200,000 for single filers, $250,000 for joint filers, or $125,000 for married filing separately.6Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax You pay 3.8% on whichever is smaller: your total net investment income, or the amount by which your income exceeds the threshold.
So a high earner selling a long-held asset actually pays 23.8%, not 20%. And interest at the top bracket sits at 40.8%, not 37%. The surtax narrows the gap between the two slightly but does not close it. You calculate the tax on Form 8960.7Internal Revenue Service. 2025 Instructions for Form 8960
Tax-Exempt Interest Is the Exception
Not every dollar of interest is taxable. Interest on bonds issued by state and local governments, known as municipal bonds, is excluded from federal gross income.8Office of the Law Revision Counsel. 26 USC 103 – Interest on State and Local Bonds That is why investors in high brackets often prefer munis. A 4% tax-exempt yield can beat a 5% taxable yield once federal tax is factored in.
Two things to note. Private activity bonds funding projects like stadiums or housing may be subject to the alternative minimum tax even though they escape regular income tax. And if you sell a muni before maturity for a profit, the profit is still a taxable capital gain. The exemption covers the interest payments, not any appreciation in the bond’s price. You still report tax-exempt interest on your return even though no tax is owed.
Losses Work Only on the Capital Side
One of the biggest practical differences between these two categories shows up when investments go badly. Sell a stock at a loss and you can offset capital gains dollar for dollar. If losses exceed gains, you can deduct up to $3,000 of the excess against ordinary income ($1,500 if married filing separately).9Office of the Law Revision Counsel. 26 USC 1211 – Limitation on Capital Losses Anything beyond that carries forward indefinitely.10Internal Revenue Service. Topic No. 409, Capital Gains and Losses
Interest has no equivalent. If a bond issuer defaults and stops paying, you cannot deduct the interest you expected but never received. You may eventually claim a capital loss when you sell the defaulted bond for less than you paid, but the lost income stream itself gives you nothing.
Watch the wash sale rule when harvesting losses. Sell a stock at a loss and buy the same or a substantially identical security within 30 days on either side of the sale, and the IRS disallows the deduction.11Office of the Law Revision Counsel. 26 USC 1091 – Loss From Wash Sales of Stock or Securities The disallowed loss adds to your basis in the replacement shares, so it is deferred rather than destroyed, but it will not help on this year’s return.
When One Investment Creates Both
Bonds are the classic case. A corporate bond pays periodic interest taxed as ordinary income, while its market price rises and falls. Sell it above your purchase price and the profit is a capital gain, short-term or long-term based on how long you held it. One bond, two lines on your return.
Mutual funds do the same. The manager buys and sells inside the fund, generating capital gains, while the fund also collects interest and dividends from its holdings. At year-end, both flow through to you as separate distributions. Year-end tax forms break them apart, and each category has to land in the right place. Treating the whole distribution as one type of income will either overpay or underpay the tax.
How Each Gets Reported
The IRS uses separate reporting pipelines for the two categories, which is another reason mixing them up creates problems.
Interest income shows up on Form 1099-INT from any payer that sent you $10 or more during the year.12Internal Revenue Service. About Form 1099-INT, Interest Income The total goes on line 2b of Form 1040. If total taxable interest exceeds $1,500, Schedule B itemizes each source.13Internal Revenue Service. Schedule B (Form 1040)
Capital gains ride a different track. Your broker sends Form 1099-B with the proceeds and cost basis for each sale. You report individual transactions on Form 8949 and summarize them on Schedule D.14Internal Revenue Service. About Schedule D (Form 1040), Capital Gains and Losses Mutual fund capital gain distributions you did not personally sell go straight to Schedule D without touching Form 8949. If your income clears the NIIT thresholds, Form 8960 pulls in both interest and gains for the 3.8% calculation.
State Taxes Change the Picture
Most states tax capital gains as ordinary income with no preferential rate, so the federal long-term advantage does not carry over on the state side in the majority of cases. A few states have no income tax at all, and a few offer partial exclusions for certain gains, but the general pattern is that the state treats a gain the same as interest. State rates run from zero to above 13%, so the combined federal-and-state bill depends heavily on where you live.
One useful exception: interest on U.S. savings bonds and Treasury securities is exempt from state and local income tax even though it is fully taxable federally.15TreasuryDirect. Tax Information for EE and I Bonds Municipal bond interest is exempt from federal tax and usually from your own state’s tax if the bond was issued in your state, though other states will typically tax it.