Form 1099-B field reference
Form 1099-B Box 1a: Description of property
Form 8949 destination
Column (a) — Description of property
Reconcile this field with the rest of the transaction before calculating gain or loss. A Form 1099-B label does not override the official basis, holding-period, or adjustment rules.
Before filing
What to check
- Match the security or asset to your trade records.
- Do not combine transactions that belong in different Form 8949 categories.
- Keep any supplemental statement that expands an abbreviated description.
How it works
Box 1a mechanics
Brokers sometimes abbreviate Box 1a — a ticker symbol and share count instead of a full security name — because the form has limited space, not because the description is optional. The description still has to be adequate to identify the specific property sold, which matters most when a single line combines multiple purchase lots with different acquisition dates or bases. Mutual funds and dividend-reinvestment positions are the most common source of this: a broker can report one aggregate sale in Box 1a while the account actually held several distinct lots behind it. Covered and noncovered lots also cannot share one Form 8949 row even if Box 1a shows them as a single sale, because they can require different reporting categories (see Box 5 and Box 12 below). When Box 1a looks abbreviated or combined, the broker's year-end supplemental statement — not the 1099-B summary page — is usually where the lot-level detail lives.
Worked example
A broker's 1099-B shows "100 sh ABC Corp" in Box 1a as a single line, but the supplemental statement reveals it combines three separate purchase lots bought on different dates at different prices. Because the lots have different acquisition dates and different bases, the taxpayer reports three separate Form 8949 rows matching the three lots on the supplemental detail, rather than one row that mirrors the Box 1a summary line.
Box 1a FAQs
Can I report one Form 8949 line for lots Box 1a shows as combined?
Only if the lots share the same acquisition date, basis, and Form 8949 category. Otherwise use the broker's supplemental statement to split the combined description back into separate lots.
What if Box 1a is truncated or just shows a ticker symbol?
Check the broker's supplemental statement or your own trade confirmations for the full security identification. Form 8949 still requires an adequate description even when the 1099-B itself shortens it.