You have to report stocks on your taxes whenever a realization event happens during the year: you sold or exchanged shares, you received dividends, or a fund you own paid you a capital gain distribution. Simply owning stock that went up in value does not create a reporting obligation. The trigger is a change in ownership or a payment to you, not a change in price. For the 2025 tax year, individual returns are due April 15, 2026.1Internal Revenue Service. When to File
Events That Force You to Report
Selling or Exchanging Shares
Any sale or exchange of stock is a taxable event for that calendar year.2Office of the Law Revision Counsel. 26 U.S.C. 1001 – Determination of Amount of and Recognition of Gain or Loss Your gain or loss is the difference between your proceeds and your cost basis, which is generally what you paid plus commissions. The transaction is complete on the trade date, not the settlement date and not the date the cash lands in your bank. It does not matter whether you reinvested the proceeds, left them in a money market sweep, or transferred them out of the brokerage.
Selling at a loss is also reportable. Losses carry real tax value, and skipping a losing trade because “nothing was gained” creates a mismatch when the IRS compares your return against the 1099 your broker filed.
Dividends, Whether You Take the Cash or Not
Dividends count as gross income in the year they are credited to your account, whether you take the cash or reinvest it automatically.3Office of the Law Revision Counsel. 26 U.S.C. 61 – Gross Income Defined Reinvestment does not defer the tax. The IRS treats you as having received the cash and then used it to buy more shares, and each reinvestment creates a new cost basis lot you will need to track for the eventual sale.
Dividends come in two flavors. Qualified dividends meet specific holding-period requirements and are taxed at the lower long-term capital gains rates. Ordinary (non-qualified) dividends are taxed at your regular income rate. Your broker splits these on Form 1099-DIV: Box 1a shows total ordinary dividends, and Box 1b shows the qualified portion.4Internal Revenue Service. Instructions for Form 1099-DIV
Mutual Fund Capital Gain Distributions
Mutual funds and some ETFs can hand you a taxable event even in a year when you never sold a share. When the fund manager sells holdings inside the fund at a profit, the fund passes the gain through to shareholders as a capital gain distribution. These appear in Box 2a of Form 1099-DIV and are treated as long-term capital gains regardless of how long you have owned the fund.5Internal Revenue Service. Mutual Funds (Costs, Distributions, etc.) 4 This catches fund investors who did nothing all year and then find a tax bill in January. Actively managed funds tend to generate larger year-end distributions than index funds.
Worthless Stock
There is one exception to the “no sale, no report” principle. If a stock becomes completely worthless, the IRS treats it as if you sold it for $0 on the last day of the tax year. That deemed sale creates a capital loss you can deduct, and your holding period runs through December 31 of that year to determine whether it is short- or long-term.6Internal Revenue Service. Losses (Homes, Stocks, Other Property) 1 You report it on Form 8949 like any other sale.
Stock You Haven’t Sold Stays Off the Return
Holding shares that have appreciated does not create any tax obligation. Unrealized gains exist only on paper until you sell, exchange, or otherwise dispose of the stock. As long as you hold the shares and receive no dividends or distributions from them, there is nothing to report for that security. The obligation stays dormant until a triggering event occurs, which is what lets long-term investors defer taxes on appreciation for decades.
How the Gain or Loss Gets Taxed Once You Report It
Holding Period Sets the Rate
How long you held the stock before selling determines the rate. Stock held one year or less produces a short-term gain or loss; stock held more than one year produces a long-term gain or loss.7Office of the Law Revision Counsel. 26 USC 1222 – Other Terms Relating to Capital Gains and Losses Short-term gains are taxed at the same rates as wages. For 2026, those ordinary rates range from 10% to 37%.8Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Long-term gains get preferential rates of 0%, 15%, or 20%, depending on your total taxable income.9Internal Revenue Service. Topic No. 409, Capital Gains and Losses
For tax year 2026, the long-term brackets are:
- 0% rate: Taxable income up to $49,450 (single), $98,900 (married filing jointly), or $66,200 (head of household).
- 15% rate: Taxable income above those thresholds up to $545,500 (single), $613,700 (married filing jointly), or $579,600 (head of household).
- 20% rate: Taxable income exceeding the 15% ceiling.
Selling a winning stock on day 364 versus day 366 can move your federal rate on the gain from as high as 37% to as low as 0%.
Losses and the $3,000 Cap
When your losses for the year exceed your gains, the excess offsets up to $3,000 of other income such as wages or interest. Married filing separately caps at $1,500.10Office of the Law Revision Counsel. 26 U.S. Code 1211 – Limitation on Capital Losses Any unused loss carries forward indefinitely and offsets gains or ordinary income in future years until it is fully used.
Losses offset gains dollar-for-dollar before the $3,000 limit applies. With $10,000 in gains and $14,000 in losses, the first $10,000 of losses wipes out the gains, the next $3,000 offsets ordinary income, and $1,000 carries to next year.
The Wash Sale Trap
You cannot sell a stock at a loss, buy back the same or a substantially identical security within 30 days before or after the sale, and still claim the deduction. This 61-day window is the wash sale rule.11Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss From Wash Sales of Stock or Securities The loss is not erased; the disallowed amount is added to the cost basis of the replacement shares, deferring the benefit until you eventually sell those shares without triggering another wash. Your broker reports the disallowed loss in Box 1g of Form 1099-B, and you report it on Form 8949 with adjustment code “W.”12Internal Revenue Service. 2025 Instructions for Form 8949
Automatic dividend reinvestment is a common way to trip this rule. Sell a stock at a loss, and if a reinvested dividend buys shares of the same stock inside the 30-day window, part or all of your loss can be disallowed.
Situations That Change What You Report
Inherited Stock
Stock received from a deceased person gets a stepped-up cost basis equal to the fair market value on the date of death. Gains that accumulated during the original owner’s lifetime are effectively erased for tax purposes.13Office of the Law Revision Counsel. 26 U.S. Code 1014 – Basis of Property Acquired From a Decedent When you sell inherited stock, you owe tax only on appreciation since the date of death, and the gain is automatically long-term no matter how recently you received it.
Gifted Stock
Gifted stock works differently. You generally inherit the donor’s original cost basis. If your uncle bought shares at $10 and gifted them to you when they were worth $50, your basis is $10. If the fair market value at the time of the gift was lower than the donor’s basis, the rules split: you use the donor’s basis to calculate a gain, and the lower fair market value to calculate a loss. If neither calculation produces a gain or loss, you report neither.14Internal Revenue Service. Property (Basis, Sale of Home, etc.)
Employer Stock: RSUs
Restricted stock units are taxed as ordinary income when they vest and shares are delivered. Your employer withholds income and payroll taxes, and the taxable amount appears on your W-2. The fair market value on the vesting date becomes your cost basis, and any difference between that value and your later sale price is a capital gain or loss reported on Form 8949 and Schedule D.
The most common RSU mistake is forgetting that the vesting was already taxed and then reporting the full sale proceeds as a gain, which double-counts the income. Many brokers report $0 or the grant-date value on the 1099-B rather than the vesting-date value, and correcting that on Form 8949 with adjustment code “B” is often necessary.12Internal Revenue Service. 2025 Instructions for Form 8949
Employer Stock: ESPPs
Shares bought through a Section 423 ESPP have their own holding-period test. If you hold the shares at least one year after purchase and two years after grant, you have a qualifying disposition. You report ordinary income only on the discount received (capped at the lesser of the discount at grant or the gain at sale), and any additional profit is a long-term capital gain.15Internal Revenue Service. Stocks (Options, Splits, Traders) 5 Sell before meeting both holding periods and the entire spread between the purchase price and the market value at purchase becomes ordinary income, with only additional gain treated as capital gain.
Employer Stock: Options
Incentive stock options generally do not create regular taxable income when exercised, though the spread at exercise can trigger the alternative minimum tax. You owe capital gains tax when you sell the shares, and if you hold them at least two years from grant and one year from exercise, the entire gain is taxed at long-term rates. Sell earlier and part of the gain converts to ordinary income.16Internal Revenue Service. Topic No. 427, Stock Options Non-qualified stock options are simpler: the spread at exercise is ordinary income reported on your W-2, and any additional gain or loss when you sell the shares is capital.
The 3.8% Net Investment Income Tax
Higher earners face an additional 3.8% surtax on net investment income, including capital gains and dividends. It applies to the lesser of your net investment income or the amount by which your modified adjusted gross income exceeds:17Internal Revenue Service. Topic No. 559, Net Investment Income Tax
- $250,000 for married filing jointly or qualifying surviving spouse
- $200,000 for single or head of household
- $125,000 for married filing separately
These thresholds are not indexed for inflation, so more taxpayers cross them each year. A single large stock sale on top of normal wage income can push you over the line even if you would not usually think of yourself as a high earner. The surtax is reported on Form 8960 and attached to your return.
Estimated Tax After a Large Gain
If you sell a large stock position mid-year, regular paycheck withholding probably will not cover the extra tax, and you may owe an underpayment penalty if you wait until April. You generally need estimated payments if you expect to owe at least $1,000 after withholding and credits, and your withholding will cover less than the smaller of 90% of the current year’s tax or 100% of last year’s tax. If your prior-year adjusted gross income exceeded $150,000 ($75,000 for married filing separately), the 100% figure becomes 110%.18Internal Revenue Service. Large Gains, Lump Sum Distributions, etc.
If you realize the gain late in the year, the annualized income installment method lets you match estimated payments to when the income was actually received, which can reduce or eliminate the penalty for earlier quarters. That calculation is done on Form 2210 with Schedule AI.19Internal Revenue Service. 2025 Instructions for Form 2210
Forms Your Broker Sends and What You File
Your brokerage sends two key tax forms early each year. Form 1099-B covers every sale or exchange, showing proceeds, purchase date, sale date, and cost basis if it was reported to the IRS.20Internal Revenue Service. Instructions for Form 1099-B (2026) Form 1099-DIV covers dividends and capital gain distributions, split between qualified and ordinary categories.4Internal Revenue Service. Instructions for Form 1099-DIV
Data from Form 1099-B feeds Form 8949, which lists each sale individually with description, dates, proceeds, basis, and any adjustments. Totals from Form 8949 flow to Schedule D of your Form 1040, which calculates your net capital gain or loss.21Internal Revenue Service. About Form 8949, Sales and Other Dispositions of Capital Assets If your 1099-B shows that basis was reported to the IRS, the gain or loss type is correct, and no adjustments are needed, you can skip Form 8949 and report those transactions directly on Schedule D.22Internal Revenue Service. Instructions for Form 8949 (2025)
When Your Numbers Don’t Match the IRS Copy
The IRS runs an automated matching program that compares broker-filed 1099s against what you reported. Discrepancies generate a Notice CP2000 proposing additional tax.23Internal Revenue Service. Topic No. 652, Notice of Underreported Income – CP2000 These notices are not audits, but they carry proposed interest if you owe more. If the discrepancy exists because you adjusted a cost basis or reported a wash sale, responding with documentation usually resolves it. Ignoring the notice leads to an automatic assessment.
Inaccurate reporting can also trigger an accuracy-related penalty of 20% of the underpayment when the IRS determines you were negligent or substantially understated income.24Office of the Law Revision Counsel. 26 U.S.C. 6662 – Imposition of Accuracy-Related Penalty on Underpayments Matching your return to your 1099 forms exactly, and documenting any legitimate adjustments, is the simplest way to avoid it.