1099-B.

In plain English

A 1099-B is a tax form a broker or barter exchange sends you and the IRS to report securities you sold during the year, such as stocks, bonds, or mutual fund shares. It lists the proceeds (the money you got from each sale) and often the cost basis (what you originally paid), plus the dates so you can tell short-term from long-term holdings. You use the numbers on it to figure your capital gain or loss and report them, usually on Schedule D and Form 8949. The broker sends one copy to you and one to the IRS, so the IRS already knows about the sales.

01Why it matters

If you sold investments and ignore the 1099-B, the IRS can flag a mismatch and send you a bill, because the form was already filed under your name.

02The math, step by step

Say you sold mutual fund shares for $5,000 that you originally bought for $3,500. Your 1099-B shows $5,000 in proceeds and may show the $3,500 cost basis. The $1,500 difference is your capital gain, which you carry onto Form 8949 and Schedule D when you file.

03What this is NOT

04Receipts

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