What Is 1099-B

Content on WhatAnswers is provided "as is" for informational purposes. While we strive for accuracy, we make no guarantees. Content is AI-assisted and should not be used as professional advice.

Last updated: April 12, 2026

Quick Answer: Form 1099-B is a tax document issued by brokers and barter exchanges to report proceeds from securities and commodities transactions to the IRS and taxpayers. The form is typically issued by January 31st each year and includes details about cost basis, gains, and losses from investment transactions executed during the previous calendar year.

Key Facts

Brokers must file Form 1099-B with the IRS when customer transaction proceeds exceed $600 in a calendar year
The deadline for brokers to issue 1099-B forms to customers is January 31st annually, with IRS filing by March 31st for electronic submissions
Over 100 million 1099-B forms are filed with the IRS annually from brokers across the United States
Form 1099-B must report adjusted cost basis, transaction dates, and distinguish between short-term and long-term capital gains
Section 1012(a) of the Internal Revenue Code requires brokers to report cost basis and sales information for stocks, bonds, mutual funds, options, and commodities

Overview

Form 1099-B is an essential tax document issued by brokers, barter exchanges, and commodity brokers to report the proceeds from securities and commodities transactions to the Internal Revenue Service (IRS) and directly to taxpayers. This form provides critical information about investment transactions executed during a calendar year, including purchase prices, sale prices, and transaction dates. The 1099-B form serves as the official record that the IRS uses to match against your personal tax return, ensuring accurate reporting of investment income and capital gains.

The purpose of Form 1099-B extends beyond simple record-keeping; it creates a transparent linkage between brokerage transactions and individual tax liability. Every broker regulated by the Securities and Exchange Commission (SEC) or Financial Industry Regulatory Authority (FINRA) is required to issue these forms when certain transaction thresholds are met. The form has evolved significantly since its introduction, with the IRS continuously updating reporting requirements to capture cost basis information, which helps taxpayers and the government accurately calculate capital gains or losses for tax purposes.

How It Works

Brokers and financial institutions generate Form 1099-B after executing investment transactions for their clients throughout the calendar year. The process involves compiling all securities sales, commodity transactions, and futures transactions, then organizing this data into a standardized format required by the IRS. Each broker must reconcile transaction data with settlement records to ensure accuracy before transmitting the completed forms to both the IRS and individual account holders.

Proceeds Amount: The gross proceeds from the sale of securities, commodities, or financial instruments, representing the total sale price before any deductions or adjustments are applied to the transaction.
Adjusted Cost Basis: The original purchase price of the security adjusted for any stock splits, dividends reinvested, return of capital distributions, or other modifications that affect the original investment cost basis calculation.
Gain or Loss Calculation: The calculated difference between the adjusted cost basis and the proceeds amount, indicating whether the investment generated a profit or loss during the entire holding period of the security.
Transaction Dates: The specific acquisition date when the security was originally purchased and the disposition date when it was sold, which determines the holding period classification and applicable tax rates.
Short-term vs. Long-term: Securities held for one year or less generate short-term capital gains taxed as ordinary income, while those held longer than one year qualify for preferential long-term capital gains tax rates of 0%, 15%, or 20%.
Wash Sale Notation: Special codes and notations indicate if losses on securities sales cannot be deducted because substantially identical securities were purchased within 30 days before or after the sale date.

Key Details

Understanding the specific components of Form 1099-B is essential for accurate tax preparation and IRS compliance. The form contains multiple boxes with distinct reporting information, each serving a specific purpose in the comprehensive tax reporting process. Brokers must separately report each transaction or group transactions by tax lot to provide complete transparency regarding investment activity throughout the tax year.

Form Component	Purpose	Typical Values	Tax Impact
Box 1a (Proceeds)	Reports gross sale amount of securities sold during the calendar year without deductions	$1,000 to $1,000,000 or more	Establishes income subject to capital gains tax calculations
Box 1b (Adjusted Cost Basis)	Shows the original purchase price adjusted for stock splits, dividends reinvested, and distributions	Varies by purchase price and holding period duration	Determines the actual gain or loss on investment transactions
Box 2 (Short-term Gain/Loss)	Indicates profits or losses from securities held less than one year from purchase to sale	Positive or negative dollar amounts	Taxed as ordinary income at the taxpayer's marginal rate (10% to 37%)
Box 3 (Long-term Gain/Loss)	Shows profits or losses from securities held more than one year from purchase date	Positive or negative dollar amounts	Eligible for preferential long-term capital gains tax rates significantly lower than ordinary income
Box 4 (Wash Sale Loss)	Denotes loss transactions disallowed under wash sale rule when identical securities repurchased	Negative amounts or zero if no wash sales occurred	Loss deduction deferred to future tax periods; cost basis of new purchase adjusted upward

The reporting deadline for brokers to transmit 1099-B forms to account holders is January 31st of the year following the transactions reported on the form. A subsequent deadline applies for filing copies with the Internal Revenue Service, which has traditionally been February 28th for paper filings or March 31st for electronic filings submitted through the IRS Filing Information Returns Electronically (FIRE) system. These deadlines ensure that taxpayers receive necessary documentation in adequate time to prepare their annual tax returns before the April 15th individual income tax filing deadline.

Why It Matters

Tax Compliance and Accuracy: Form 1099-B enables the IRS to cross-reference reported investment gains and losses against individual taxpayer returns through matching programs, ensuring compliance and reducing the risk of erroneous tax calculations and underpayment penalties.
Capital Gains Tax Calculation: The form provides exact cost basis and proceeds information necessary to calculate short-term and long-term capital gains or losses, which are taxed at dramatically different rates under current federal tax law and regulations.
Audit Documentation and Defense: Possessing accurate and organized 1099-B forms protects taxpayers during IRS audits by providing authoritative third-party documentation of transaction details originally reported to the government by financial institutions.
Investment Performance Tracking: The detailed transaction information helps investors maintain comprehensive records of their portfolio activity, supporting informed financial planning, performance analysis, and strategy adjustments for future investments.
Wash Sale and Tax Loss Harvesting: Brokers use 1099-B reporting to identify and flag wash sale transactions, where investors have repurchased substantially identical securities within 30 days, affecting the deductibility of tax losses used for tax-loss harvesting strategies.

Form 1099-B represents a critical bridge between your brokerage account activity and your tax obligations to the federal government. By maintaining organized records of these forms and understanding their components and implications, investors can ensure accurate tax reporting while maximizing legitimate tax-saving strategies and investment techniques. The investment in understanding 1099-B documentation and filing requirements pays dividends through improved tax efficiency, reduced compliance risk with IRS regulations, and enhanced financial management of investment portfolios.