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1099-B Box 5 Noncovered Security and Box 12 Basis Reported

Updated September 30, 2026. Quick answer: Box 5 of Form 1099-B is checked when the broker is reporting the sale of a noncovered security. When it is checked, the broker does not have to fill in basis. Box 12 says whether basis was reported to the IRS anyway.

Schedule D and Schedule E (Form 1040) for 2025, read line by line: Schedule D line 1a and Schedule D line 8a.

Form 8949 for 2025, read code by code: Form 8949 boxes A to L, Form 8949 code M and Form 8949 code O.

Read box by box from the IRS form text: Form 1099-OID box 6, Form 1099-DA boxes 1c, 1d and 1e and Form 1099-DA box 1g.

The IRS form or worksheet behind this, read line by line: Form 8949 instructions.

Box 5

The instruction reads: “You may check the box if reporting the sale of a noncovered security. Do not check this box if reporting the sale of a covered security.” The 1099-B instructions read here are the 2026 edition on irs.gov. Those are instructions to the payer that files the form, so they show what a box is meant to hold, not what tax follows from it.

What checking Box 5 excuses

The instructions say “If you check this box, you do not have to complete boxes 1b, 1e, 1f, 1g, and 2, and you do not have to check box 12.” That is why Box 1e is often blank on a noncovered sale. What makes a security covered is on the Box 1d and 1e page.

Box 12

Box 12 is for basis reported to the IRS. The instruction says to check it if “You are not checking box 5, or” or if “You are checking box 5 but are reporting basis to the IRS in box 1e anyway.”

What the instructions do not say

They do not tell you where to find basis when it is missing. Your own purchase records and the account provider are the place to start.

Common mistakes

  • Reading a blank Box 1e as an error. On a noncovered sale it may be blank by design.
  • Assuming Box 12 is checked on every form. It depends on Box 5 and on whether basis was reported anyway.
  • Treating Box 5 as a judgment about your gain. It describes the security.

Related: 1099-B Box 1d Proceeds and Box 1e Cost Basis Explained, and 1099-B Box 2: Short-Term or Long-Term Gain or Loss.

Every box in one place: the 1099-DIV, 1099-INT and 1099-B boxes table. If your withdrawal came from an IRA or 401(k), see the Form 1099-R Box 7 codes.

Sources

Source: the IRS instructions for the filer of each form, read at irs.gov on September 30, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.