To file a federal income tax return for share trading, you report every stock sale on Form 8949, carry the totals to Schedule D, and attach both to your Form 1040. Your broker’s 1099-B is the starting document. Sales held one year or less are short-term and taxed at ordinary income rates; sales held longer than a year are long-term and taxed at preferential rates. Dividends and interest from the same account get reported separately, and a handful of rules, especially the wash sale rule and the $3,000 net loss cap, can change what actually lands on your return. The federal filing deadline for the 2026 tax year is April 15, 2027.
Start With the Forms Your Broker Sends
By the end of January, your brokerage posts or mails three forms that supply almost every number you’ll need:
- Form 1099-B lists every security you sold during the year with the description, date acquired, date sold, proceeds, and cost basis. It also flags whether the cost basis was reported to the IRS, which determines how you report the sale.1Internal Revenue Service. Instructions for Form 1099-B
- Form 1099-DIV reports ordinary and qualified dividends, and shows any foreign taxes withheld on international holdings.2Internal Revenue Service. About Form 1099-DIV, Dividends and Distributions
- Form 1099-INT reports interest of $10 or more from bonds, cash sweeps, or money market positions in the account, taxed at ordinary income rates.
Shares you transferred in from another broker or inherited often arrive with incomplete basis information. If the 1099-B is missing cost basis, reconstruct it from trade confirmations, monthly statements, and transfer documents before you start the return. Cost basis errors are one of the most common triggers for an IRS automated notice.
Commissions and fees you paid to buy or sell shares are not deductible as separate items. They fold into your cost basis, which reduces your gain or increases your loss when you sell.
Report Sales on Form 8949 and Schedule D
Form 8949 is where individual stock sales get listed. Part I is for short-term transactions (held one year or less), and Part II is for long-term transactions (held more than a year). Each sale takes a row with the stock description, date acquired, date sold, proceeds, cost basis, and any adjustment codes.3Internal Revenue Service. Instructions for Form 8949 – Sales and Other Dispositions of Capital Assets A wash sale, for example, requires a specific code in Column (f) and the disallowed loss amount in Column (g).4Internal Revenue Service. Form 8949 – Sales and Other Dispositions of Capital Assets
There’s a shortcut most filers can use. If your 1099-B shows that the cost basis was reported to the IRS and you have no adjustments to make, you can skip Form 8949 and enter the totals directly on Schedule D, line 1a for short-term or line 8a for long-term.3Internal Revenue Service. Instructions for Form 8949 – Sales and Other Dispositions of Capital Assets For anyone with hundreds of trades and no wash sales or basis corrections, this saves real time.
The totals from Form 8949 flow to Schedule D, which combines short-term and long-term results into a single net gain or loss.5Internal Revenue Service. Instructions for Schedule D (Form 1040) That net figure moves onto your Form 1040. Most tax software imports 1099-B data directly from your broker, which eliminates manual entry.
How Long You Held the Shares Sets the Rate
Holding period is the single most important variable on your return. Shares sold after one year or less produce short-term capital gains taxed at your ordinary income rate. Shares held longer than a year produce long-term capital gains taxed at preferential rates.6Office of the Law Revision Counsel. 26 U.S. Code 1222 – Other Terms Relating to Capital Gains and Losses
For 2026, ordinary income rates run from 10 percent to 37 percent across seven brackets.7Internal Revenue Service. Federal Income Tax Rates and Brackets Long-term capital gains rates for 2026 are:
- 0 percent on taxable income up to $49,450 (single) or $98,900 (married filing jointly)
- 15 percent from $49,451 to $545,500 (single) or $98,901 to $613,700 (married filing jointly)
- 20 percent above those thresholds
A single filer in the 24 percent ordinary bracket who sells a stock at 13 months instead of 11 could cut the tax rate on that gain nearly in half. Under federal law, shares you buy and sell are capital assets, and the profit is a capital gain.8Office of the Law Revision Counsel. 26 U.S. Code 1221 – Capital Asset Defined
Dividends and the Net Investment Income Tax
Dividends from most U.S. and some foreign stocks are taxed at the same preferential rates as long-term gains, but only if you meet a holding-period requirement: at least 61 days during the 121-day window that begins 60 days before the ex-dividend date.9Internal Revenue Service. IRS Gives Investors the Benefit of Pending Technical Corrections on Qualified Dividends Dividends that miss the test are ordinary dividends, taxed at your regular income rate. Your 1099-DIV separates the two.
High earners owe an additional 3.8 percent surtax on net investment income, which includes capital gains, dividends, and interest from your brokerage account. It applies when modified adjusted gross income exceeds $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately).10Office of the Law Revision Counsel. 26 U.S.C. 1411 – Imposition of Tax The 3.8 percent hits the lesser of your net investment income or the amount by which your income exceeds the threshold. These thresholds are not indexed for inflation. If it applies, report it on Form 8960.
Watch for Wash Sales
You cannot sell a stock at a loss and buy it back right away to claim the deduction. If you purchase a substantially identical security within 30 days before or after selling at a loss, the IRS disallows the loss for the current year.11Office of the Law Revision Counsel. 26 U.S.C. 1091 – Loss From Wash Sales of Stock or Securities The disallowed amount doesn’t vanish. It gets added to the cost basis of the replacement shares, deferring the tax benefit until you sell those in a clean transaction.
Most people trip over this without realizing it. Dollar-cost averaging every two weeks and selling some shares at a loss in between purchases usually triggers a wash sale. Brokers flag wash sales on your 1099-B, but only within a single account. If you sell at a loss in one brokerage account and buy the same stock in another account or in your IRA within the 30-day window, catching that is on you.
When Losses Exceed Gains
If your total capital losses come in higher than your total capital gains, you can deduct the excess against ordinary income, but only up to $3,000 per year, or $1,500 if married filing separately.12Office of the Law Revision Counsel. 26 U.S.C. 1211 – Limitation on Capital Losses Anything left over carries forward to future tax years indefinitely.13Internal Revenue Service. Topic No. 409, Capital Gains and Losses
A $30,000 losing year offsets any gains first, then $3,000 of wages or other ordinary income. The rest waits for future years. You calculate the carryover using the Capital Loss Carryover Worksheet in the Schedule D instructions. Keep your prior-year returns accessible so you don’t lose track.
Pick Your Cost Basis Method Before You Sell
When you’ve bought the same stock at different times and prices, the cost basis method decides how much gain or loss each sale produces. The IRS default is first-in, first-out, which treats the earliest shares as sold first.14Internal Revenue Service. Publication 551 – Basis of Assets In a rising market, that usually produces the largest taxable gain.
If you specifically identify which shares you’re selling at the time of the trade, you can choose the lot with the most favorable tax result, such as selling higher-cost shares first to reduce a current-year gain. Most brokerages let you select lots on the platform before executing the sale. Mutual fund shares also allow an average-cost method, which pools every share and divides by the total. The critical piece: you cannot retroactively change which lots were sold after the trade settles.
If You Trade as a Business
Most people who buy and sell stocks are investors in the eyes of the IRS. Trader status is different. If you make frequent, short-term trades aimed at daily price swings rather than long-term growth, the IRS may treat your activity as a business, which lets you deduct data subscriptions, platform fees, and home office costs on Schedule C. To qualify, trading must be substantial, continuous, and regular. Even with trader status, your trading gains and losses are still capital gains and losses unless you make a special election, and they aren’t subject to self-employment tax.15Internal Revenue Service. Topic No. 429, Traders in Securities
Qualifying traders can make a Section 475(f) mark-to-market election, which removes the $3,000 capital loss cap (losses become ordinary) and makes the wash sale rule inapplicable to trading securities.15Internal Revenue Service. Topic No. 429, Traders in Securities The election must be filed by the original due date of the return for the year before you want it to take effect. To use mark-to-market for 2026 trading, the election was due by April 15, 2026, with the 2025 return. Under mark-to-market, positions held at year-end are treated as sold on December 31 at fair market value. If you also hold long-term investments, keep them in a separate account and identify them as investment holdings in your records on the day you acquire them.
Estimated Tax Payments During the Year
Trading income isn’t subject to payroll withholding, so profitable years usually mean quarterly estimated payments. The 2026 due dates are:16Internal Revenue Service. 2026 Form 1040-ES
- First quarter: April 15, 2026
- Second quarter: June 15, 2026
- Third quarter: September 15, 2026
- Fourth quarter: January 15, 2027
You can skip the January 15 payment if you file the full 2026 return and pay any balance by February 1, 2027. To avoid an underpayment penalty, generally pay at least 90 percent of the current-year tax or 100 percent of the prior year’s tax, rising to 110 percent if your prior-year adjusted gross income exceeded $150,000.17Office of the Law Revision Counsel. 26 U.S.C. 6654 – Failure by Individual to Pay Estimated Income Tax For traders whose income swings from year to year, the prior-year safe harbor is usually simplest because the number is known in advance.
Filing Deadlines, Extensions, and Late Penalties
The deadline to file your 2026 federal return is April 15, 2027. You can request an automatic six-month extension to October 15, 2027, but the extension only covers the paperwork. Any tax owed is still due April 15.
Missing the deadline without an extension runs two penalties at once. The failure-to-file penalty is 5 percent of unpaid tax per month or partial month, capped at 25 percent.18Internal Revenue Service. Failure to File Penalty The failure-to-pay penalty is 0.5 percent per month, also capped at 25 percent. For returns filed more than 60 days late, the minimum failure-to-file penalty is the lesser of $525 or 100 percent of the unpaid tax.
The filing penalty is ten times the payment penalty per month. If cash is short but the numbers are ready, file on time and set up a payment plan. The IRS drops the failure-to-pay rate to 0.25 percent per month while an installment agreement is in place. Keep a copy of the signed return and every supporting schedule for at least three years, which is the standard audit window.