How To Report Stock Sales On Your Tax Return

To report stock sales on your tax return, transfer every transaction from your broker’s 1099-B onto Form 8949, then calculate the gain or loss by subtracting your cost basis from the proceeds. After that, you carry the totals to Schedule D. Schedule D ultimately flows to your Form 1040. This process is the same whether you sold ten shares of a blue-chip stock or a single lot of a penny stock. The IRS expects the details to match your broker’s records exactly. The key is to work through each transaction methodically. Use the codes and columns on Form 8949 to reconcile any discrepancies before the totals hit Schedule D.

Matching your 1099-B to report stock sales on form 8949

Your broker’s 1099-B is not a tax form itself. It’s a statement of proceeds, and you must translate it line by line onto Form 8949. Look at the 1099-B’s boxes. Box 1a shows the date of sale. Box 1b shows the date acquired, or “various” for average-cost basis. Box 1c shows the proceeds. Box 1e shows your cost basis. Box 1d shows any wash sale disallowed loss. The critical distinction is between covered and noncovered shares. Covered shares, with Box 6 checked, are those acquired after January 1, 2011, or 2012 for mutual funds, and the broker reported your cost basis to the IRS. Noncovered shares, with Box 6 unchecked, are older, and the broker did not report basis. You must still report the sale, but the IRS has no pre-filled basis to compare against. On Form 8949, Part I is for short-term transactions held one year or less. Part II is for long-term transactions held more than one year. Each row asks for the description, like “100 sh. XYZ Corp.,” the dates, the proceeds, the cost basis, and any code from column (c) that indicates an adjustment. If your 1099-B shows a covered share with a basis, you simply copy the numbers. If it shows a noncovered share, you still enter the proceeds but you must calculate the basis yourself from your own records, because the IRS has no matching data.

Adjusting your cost basis and wash sales

A wash sale occurs when you sell a stock at a loss and buy a “substantially identical” stock within 30 days before or after the sale. The IRS disallows that loss for the current year, but you don’t lose it forever. You add the disallowed amount to the cost basis of the new shares. On Form 8949, you report the original sale with the loss. Then in column (g) you enter the adjustment code “W” and the dollar amount of the disallowed loss. For example, imagine you sold 100 shares at a loss and bought 100 shares of the same company 20 days later. Your broker’s 1099-B will show a wash sale disallowed loss in Box 1d. You enter the proceeds and basis as shown. Then in column (g) you type “W” and the adjustment amount. The exact dollar figure for that adjustment is set by your broker’s calculation on the 1099-B, and you should verify the current year’s threshold and rules on the official IRS website. That adjustment increases your gain or decreases your loss on the sale, making the final number match the reality that you cannot claim that loss this year. The broker typically calculates this for you on covered shares. For noncovered shares, or if you transferred shares between accounts, you must compute it yourself. The same logic applies to adjustments for nondividend distributions with code “L” or accrued market discount with code “H.” The wash sale is the most common mistake individual investors make. Double-check every loss that was followed by a repurchase within 30 days.

When your 1099-B is wrong or missing

If your 1099-B shows a zero cost basis or is missing entirely, do not guess. The IRS receives a copy of your 1099-B. If your Form 8949 does not match, you will trigger a notice. For a zero basis, the most common cause is that the shares were inherited, gifted, or acquired through a dividend reinvestment plan where the broker never tracked the original cost. In that case, you must reconstruct the basis using your own records. Then use adjustment code “B” for short-term or “T” for long-term in column (g) to correct the broker’s number. For example, if your broker reports a $0 basis but you know you paid an amount originally, you enter $0 as the basis. Then in column (g) type “B” and the negative amount to reduce the gain. The specific dollar value you enter is your own reconstructed cost, which falls into a range set by your purchase records, and you should confirm the reporting method on the official IRS website. If the 1099-B is incorrect because of a corporate action like a stock split or merger, use code “C” for a short-term adjustment or “V” for long-term. Attach a statement explaining the change. If the 1099-B is missing entirely because you sold shares from an account that did not issue one, which is rare but possible for foreign brokers, you still report the sale on Form 8949. You must write “No 1099-B received” in the description column and be ready to prove your basis with your own statements. The IRS is less concerned about the adjustment itself than about the total net gain or loss being correct. Using the proper code and keeping a copy of your worksheet is your best defense. These adjustments also matter when you deal with related topics like taxes on investments, which is the hub for this topic, and you can cross-reference the rules for how to report stock sales on your tax return, what happens to taxes when i sell an inherited stock, and whether are crypto and digital asset sales taxed, each has its own quirks, but the Form 8949 mechanics are identical.

The one rule that separates a correct tax filing from an audit flag is that every single transaction from your 1099-B must appear on Form 8949 with a basis that matches the IRS’s copy or a documented adjustment code explaining the difference.

Frequently Asked Questions

Do I need to report a stock sale if my broker did not send me a 1099-B?

Yes, you must report every sale, even if no 1099-B was issued. Use your own trade confirmations to fill out Form 8949, and write “No 1099-B” in the description column to explain the missing document.

What if I sold shares in a company that went bankrupt and the stock is now worthless?

You still report the sale, but you may be able to claim a capital loss for the full amount of your basis if the stock became worthless in the same year. Use the date of the bankruptcy filing or the last trading day as the sale date, and attach a statement explaining the situation.

How do I handle a stock split that changes my cost basis mid-year?

You do not adjust the proceeds; you adjust the per-share basis. For example, if you bought shares at a specific price and a split occurs, you now have more shares with a lower per-share basis. The exact per-share price is a fact set by the corporate action and your original purchase records, and you should verify the adjusted basis against the official guidance on the IRS website. When you sell, report the actual sales price and your adjusted per-share basis, and note the split in the description.

Can I use the average cost method for mutual funds instead of specific identification?

Yes, but only for mutual funds and only if you have held the shares for more than one year. Average cost is not allowed for individual stocks. If you elect average cost, your broker will report the average basis on the 1099-B, and you simply copy it to Form 8949.