U.S. · Tax forms
1099-B box 1e cost or other basis.
Where the number comes from, when it is blank, and what to do when it is wrong.
Box 1e is the adjusted basis of the securities you sold, normally what you paid plus commissions and transfer taxes. Gain or loss is box 1d (proceeds) minus box 1e. It is blank, not zero, when the security is noncovered and box 5 is checked. If box 1e is wrong, you correct it on Form 8949 with code B, not by changing the broker's form.
Estimate gain or loss from boxes 1d, 1e and 1g
Result
How a broker builds box 1e
| Situation | What the broker reports in box 1e | What it means for you |
|---|---|---|
| Cash purchase | Total cash paid plus commissions and transfer taxes to buy the security (the "initial basis"). | Your starting basis. Fees you paid to buy are already included. |
| Wash sale replacement | Adjusted basis is increased by the disallowed loss reported in box 1g on the earlier sale. | A loss you could not use yet moves into the basis of the shares you bought. |
| Average basis method | Total basis of identical shares in the account divided by the number of shares, regardless of holding period. | Typical for mutual fund shares; the broker applies it if you elected it or it is the broker's default. |
| Short sale | Adjusted basis of the security delivered to close the short sale. | Basis is not the price at which you first sold short. |
| Cash in a corporate merger | Only the net reduction in basis attributable to the cash (boot) reported in box 1d. | In the IRS example, $5,000 of MNO stock became $4,700 of PQR stock plus $800 boot, so box 1e shows $300. |
| Gift transferred in | The basis from the transfer statement, with the gift basis rules applied. | If neither gain nor loss is recognized under those rules, the broker may treat basis as equal to proceeds. |
| Noncovered security, box 5 checked | Left blank unless the broker chooses to report it. | You find the basis in your own records and report it on Form 8949. |
| Basis really is zero | -0-, entered only when the securities actually had a basis of zero. | A blank is not the same as zero; do not treat a blank as zero basis. |
Covered and noncovered securities
The 1099-B instructions define a covered security by when and how it was acquired: for example, stock acquired for cash in an account after 2010, or average-basis stock acquired after 2011. A noncovered security is anything that is not covered, such as stock whose basis comes from a noncovered security after a split or reorganization. For a noncovered security the broker may check box 5 and skip box 1e. Because the broker is not penalized for getting those boxes wrong, check the figure against your own trade confirmations.
When box 1e is wrong
The Form 8949 instructions use code B when the basis in box 1e is incorrect. The fix depends on the Form 8949 box. If the sale belongs on box B or E (basis not reported to the IRS), put the correct basis in column (e) and -0- in column (g). If it belongs on box A or D (basis reported to the IRS), enter the broker's figure in column (e) anyway and correct it with an adjustment in column (g). Your gain is then column (d) minus column (e) combined with column (g).
Worked example
This is an illustration using the IRS wash sale numbers. A broker shows proceeds of $600 in box 1d, basis of $1,000 in box 1e and a disallowed wash sale loss of $300 in box 1g. The raw result is a $400 loss. Form 8949 adds the $300 as a positive adjustment with code W, so the loss you can claim now is $100. The calculator above does the same arithmetic.
Where next
To see how the broker's date and basis flags decide which Form 8949 box you use, read 1099-B box 5 and box 12. For the disallowed-loss number, see box 1g.
Sources
- Instructions for Form 1099-B: Box 1e, covered and noncovered security definitions, adjusted basis, average basis method, wash sale and merger examples.. Read November 2, 2026. (IRS page last reviewed April 30, 2026.)
- Instructions for Form 8949 (2025): Column (e), Column (g), and the code B row of the columns (f) and (g) table.. Read November 2, 2026. (IRS page last reviewed April 30, 2026.)
Line and box numbers are those printed in the IRS instructions named above and can change from year to year; match each box by its label.
Frequently asked questions
What is box 1e on a 1099-B?
Box 1e is the cost or other basis: the adjusted basis of the securities sold, normally the cash paid plus commissions and transfer taxes to buy them. Gain or loss is box 1d minus box 1e.
Why is box 1e blank?
A broker may leave box 1e blank when the security is noncovered and box 5 is checked. A blank is not a basis of zero; the broker enters -0- only when the basis actually was zero.
What do I do if box 1e is wrong?
Use code B on Form 8949. Depending on the Form 8949 box, you either enter the correct basis in column (e) or enter the broker's figure and correct it with an adjustment in column (g).
Does box 1e include commissions?
Yes. The IRS defines initial basis as cash paid plus the commissions and transfer taxes to buy the security. Selling commissions and transfer taxes reduce the proceeds in box 1d instead.
Is box 1e affected by a wash sale?
Yes. When a loss is disallowed, the broker increases the adjusted basis of the replacement securities by the amount shown in box 1g on the earlier sale.
Not tax advice
This page summarizes IRS instructions, mostly written for the people who prepare the form, and is not tax, legal or financial advice. The payer, a CPA or an enrolled agent can confirm what a box or code means for your return. Everything runs in your browser; nothing you enter is sent anywhere.