Although the tax legislation in Congress has no impact on 2017 taxes or tax returns, the 2018 tax season still has the potential to be confusing if you sold stock in 2017.

Alert: For stock sales, you must file with your tax return IRS Form 8949 and Schedule D. To avoid overpaying taxes, be aware of the issues involving the cost basis for stock sales reported on IRS Form 1099-B.
You must file both Form 8949 and Schedule D when reporting stock sales on your tax return.

By the end of January, you should have received your IRS Form W-2, as usual. It will show any ordinary income stemming from stock options or employee stock purchase plans.

If you sold shares during 2017, before mid-February your brokerage will send you IRS Form 1099-B, which brokers usually reformat into their own substitute statement. Form 1099-B reports stock sales made during the year. In addition, you will also receive IRS Form 3922 if you purchased ESPP shares in 2017 and IRS Form 3921 if you exercised ISOs in 2017.

Puzzled by what to do with your W-2, the revised 1099-B, or Forms 3921 and 3922? Don't quite know how and where to report sales of company stock on Form 8949 and Schedule D? Even if you hire someone to handle your tax return (tax specialists are helpful), you can nevertheless benefit by knowing some of the basics presented in this article about income tax reporting for company stock. The Tax Center of this website also provides annotated diagrams of Form 8949 and Schedule D showing how to report stock sales on tax returns.

If you need to report income from restricted stock or restricted stock units, see a companion article.

What's New For The 2018 Tax Season

The tax legislation in Congress does not affect tax-return reporting of 2017 income. However, it is worth remembering that a couple of years ago, the IRS introduced big changes in the Form 1099-B reporting for stock sales. These created confusion in the Form 8949 reporting for sales of stock acquired from equity compensation, and they raised the risk of overpaying taxes. For the 2018 tax-return season (covering stock sales in 2017), the forms and rules have not changed, though the overpayment risk remains. With sales of stock acquired from equity compensation, it remains important to understand the cost-basis rules covered below.

Tax-Reporting Errors To Avoid

Here are tips for sidestepping common pitfalls (see also the related FAQs on mistakes involving stock options, restricted stock/RSUs, ESPPs, and SARs).

Mistake No. 1: Double-Counting Option Income

Don't let your W-2 trip you up. When you exercise NQSOs, even if you don't sell any shares, the difference between the exercise price and the fair market value (FMV) of those shares will be treated as ordinary income and included in Box 1 of your Form W-2 and in the other boxes for state and local income, Social Security up to the yearly maximum, and Medicare, along with the amount withheld (see the FAQ showing an annotated diagram of Form W-2 for NQSOs). For ISOs, only when you make a disqualifying disposition will the income appear on your W-2, but no withholding occurs (see the FAQ showing an annotated diagram of Form W-2 for this situation).

Don't make the painfully expensive mistake of double-counting income!

Companies also specify NQSO income by putting it in Box 12 of Form W-2, using Code V (not required for ISOs, restricted stock/RSUs, or tax-qualified ESPPs). When you look at the line for "Other income" on your Form 1040 (Line 21 on the 2017 form), don't make the mistake of listing the amount shown in Box 12 of your W-2 or any income already included in Box 1 for stock compensation. You're already including it as part of Line 7 of the Form 1040 (wages, salaries, tips, etc.). That would be painfully expensive double-counting of income!

Alert: It is also easy to make the same mistake with ESPPs that are not tax-qualified, as the W-2 tax reporting is the same as for nonqualified stock options.

To double-check how much compensation came from salary versus options, compare your year-end salary paycheck stub with your W-2. The difference between the two statements should reveal your option income.

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Mistake No. 2: Failing To Report Sales

If you sold shares during the tax year, your broker will send you IRS Form 1099-B showing the sales. Using the 1099-B, you report on IRS Form 8949 and Schedule D the sales proceeds, along with the other information from the 1099-B. While the 1099-B now includes more information than it used to, it does not show withheld taxes, unless backup withholding was triggered.

Be sure you do this reporting even for a cashless exercise in which all the income is already on your W-2.

Even with a cashless exercise or immediate sale of ESPP shares at purchase in which all the income is on your W-2 and you appear to have no additional gains on the sale, be sure you report the sale. In some cases with a cashless exercise, there will still be a small short-term gain or loss, depending on the commission. As explained in the next section, about the tax basis, you will not be overreporting your income. In special situations where your broker is not required to give you a Form 1099-B for the cashless exercise (see a related FAQ) you should still report the sale on Form 8949.

Alert: Even when you have no income for your sale beyond what appears on your W-2, you still must report the sale on Form 8949 and Schedule D. If you don't, you can expect a letter from the IRS (see a related FAQ). The IRS has expanded its technology over the past few years and can easily match and compare e-filed information documents (e.g. Form 1099-B) against filed tax returns.

Mistake No. 3: Miscalculating The Tax Basis

When you sell your shares, the sales price (again, after commissions) minus your cost basis equals your capital gain or loss. The revised 1099-B reports your tax basis in Box 1e (instead of boxes, your broker's substitute statement may use columns with the same numbering). However, the cost-basis information reported to the IRS in Box 1e of Form 1099-B may be too low, or the box may be blank. This is because the rules for cost-basis reporting are mandatory only for stock acquired in 2011 and later. In addition, for shares acquired from option grants made before 2014, brokers can include as part of the basis the compensation triggered at exercise. Furthering the potential confusion, shares not acquired for cash, such as shares from a stock-swap exercise, SARs exercise, or restricted stock vesting, are considered noncovered securities.

Securities acquired through stock plans: status by grant type

Covered securities Noncovered securities
1. Stock option exercise
2. ESPP purchase
1. Restricted stock or RSU vesting
2. Performance share or PSU vesting
3. Stock appreciation rights exercise
On Form 8949, always use the cost basis and gross proceeds on Form 1099-B. These are the figures the IRS receives.

On Form 8949, always use the cost basis and the gross proceeds shown on Form 1099-B or the reformatted substitute statement from your broker. You want to report the figures that the IRS receives. It is up to you—not your company, your broker, or the IRS—to make any necessary modifications on your Form 8949. A few fixes for common situations:

  • Cost basis in Box 1e of Form 1099-B too low? Report it in column (e). Make the appropriate adjustment in column (g) of Form 8949 and put Code B in column (f).
  • Box 1e of Form 1099-B is blank or shows zero? Report the correct basis in column (e) of Form 8949.
  • Form 1099-B does not (though it should) subtract commissions or other fees from the proceeds? Don't add them to your cost basis on Form 8949. Instead, adjust the amount in column (g) and add Code E in column (f).
Alert: You must accurately report your cost basis on Form 8949, making any adjustments required, to avoid being taxed twice on income already reported as part of your compensation on your W-2. Some people incorrectly use the exercise price as the basis for their NQSOs (a similar mistake lurks with ESPPs too). But your basis in the stock is the amount you paid to exercise the options (or purchase ESPP stock) plus the amount of income included on your W-2 as a result of the exercise (or purchase).

Each type of exercise method can create its own confusion with the reporting of shares sold either at exercise or later. For example, with a sell-to-cover exercise, if you sold only some of the shares at exercise you don't want to report on your Form 8949 and Schedule D the cost basis for all the shares exercised. This would result in a much larger tax basis and a capital loss for these shares sold.

In the Tax Center on this website, see our tax-return video and the special section Reporting Company Stock Sales. It has annotated diagrams of Form 8949 and Schedule D for reporting situations involving sales of all types of stock compensation and ESPPs.

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Mistake No. 4: Fouling Up Your AMT Calculation By Excluding ISOs

Sometimes people don't tell their accountants or the IRS about incentive stock options that they have exercised and held; they may believe that exercise without a sale is a nontaxable event. So they figure in good faith that the accountant or IRS doesn't need to know. Others may have forgotten about ISO exercises, particularly since the stock value isn't reflected in W-2s.

Alternatively, you may know too well about your expected AMT hit on paper profits for last year's exercise and hold. Since there is no W-2 paper trail, you wonder why your accountant or the IRS needs to know about your exercise.

An audit could reveal that the earlier ISO exercise and hold was not considered in the AMT calculation.

The problem with this omission is that it will make your alternative minimum tax calculation incorrect. The reason: when you exercise ISOs and then hold the shares through the calendar year of exercise, you do not have current regular income. Instead, you have income for AMT purposes.

In addition, when the time comes to sell the stock, this is reported to the IRS. An audit could reveal that the earlier ISO exercise and hold was not considered in the AMT calculation. Along with paying the back taxes you owe, you would then pay interest and penalties too. If you cannot come up with the cash for the taxes that are due with your return for the AMT, you may want to work out a payment plan with the IRS.

Alert: ISO exercises in a given tax year are reported on Form 3921 early in the following year. This form helps you collect information for reporting sales of ISO shares on your tax return and assists in the AMT calculation at exercise. The IRS also receives a copy of the form, ensuring that the IRS knows about your ISO exercise and therefore any AMT triggered by the exercise income. For details, see the related article elsewhere on this website.

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The AMT is basically a pre-payment of the tax on ISOs. IRS Form 6251 is used to figure the amount, if any, of your AMT.

Mistake No. 5: Neglecting To Carry Forward Your AMT Credit

The AMT is basically a pre-payment of the tax on ISOs. IRS Form 6251 is used to figure the amount, if any, of your AMT. You report the ISO exercise spread on Line 14. Although it can take longer than you like to recover the money you paid, you get a credit for AMT in subsequent years. You need to calculate your AMT in every future year until the credit is used up, even before selling the ISO stock. Traditionally, the credit each year is limited to the amount by which your ordinary income tax exceeds your AMT, and any unused credit is carried forward (for information on the new refundable credit, see the alert below).

Some people forget about a previous year's adjustment for AMT and fail to carry credits forward to use in years when their regular income exceeds AMT income. To avoid this error, look at your past taxes and see whether you had any AMT credit eligible to be carried over into this year. If so, IRS Form 8801 is where you'll figure your credit. Form 8801 is also used to compute how much of an AMT credit, if any, you'll be able to carry forward to next year. You can download forms and instructions at

Alert: In what was called the refundable AMT credit, for AMT credits over three years old you could alternatively recover up to 50% per year of the remaining unused credit. However, this provision was not extended beyond the 2012 tax year. (For details, see the FAQ on the refundable AMT credit.)

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Mistake No. 6: Inadvertently Overpaying AMT In The Year Of An ISO Sale

The tax rules that apply to selling ISO shares after paying AMT perplex even experts. Once you have AMT for your ISO stock, you essentially need to keep two sets of records: one for ordinary income tax and the other for ongoing AMT calculations. You must do this to properly use the credit to reduce future taxes.

ISO stock is an example of what tax experts call "dual basis assets" because it has a different basis for regular income tax and another one for the AMT. As Kaye Thomas explains in his excellent book Consider Your Options, "The AMT gain or loss on a sale of that asset won't be the same as the regular tax gain or loss. If you're not alert to this situation you may end up needlessly paying more tax than required."

The key to avoid paying or calculating more AMT than is required for your ISO stock sale is also to report (as a negative amount) your "adjusted gain or loss" on Line 17 of Part I of AMT Form 6251.

As you do with any securities sale, you report the sale of the stock on Form 8949 and Schedule D (but you also prepare an AMT version that you do not file). Capital gain or loss for your ordinary income tax will depend on the stock's exercise price and whether the stock price at sale was less than, equal to, or greater than the ISO exercise price. Your AMT basis will be higher than your regular tax basis, as it includes the spread at exercise. The key to avoid paying or calculating more AMT than is required for your ISO stock sale is also to report (as a negative amount) your "adjusted gain or loss" on Line 17 of Part I of AMT Form 6251.

This amount is the difference between your regular income tax and AMT capital gains. But in some situations when you are selling the stock at an AMT loss, this negative amount could be restricted by the $3,000 annual limitation on capital losses. The instructions for IRS Form 6251 include a detailed example of this loss sale situation.

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Mistake No. 7: Miscalculating Taxes With ESPPs

Employee stock purchase plans that comply with Section 423 of the Internal Revenue Code allow you to buy shares through after-tax payroll deductions at a discount of up to 15% off your company's fair market value. There is no withholding on a purchase in a tax-qualified ESPP, regardless of whether you held or sold shares at exercise/purchase.

Alert: You should not include the discount in the year of purchase unless you also sell the shares in the same year. If you hold the shares for more than one year after the date of purchase, and more than two years after the beginning of the offering period, you'll have ordinary income in the year of sale equal to the lesser of either the actual gain upon sale or the purchase price discount at the beginning of the offering (see a related FAQ with examples of the tax treatment).
Regardless of how long you hold ESPP shares, your tax basis is the purchase price plus whatever amount of income you recognized.

The full discount doesn't qualify for capital gains treatment even if you hold your stock for longer than one year. But beyond the discount, all additional gain is treated as long-term capital gain. When you don't satisfy the ESPP holding periods, you have compensation income in the year of sale equal to the spread at purchase, i.e. the difference between the fair market value of the stock on the purchase date and the discounted price you actually paid for it.

Regardless of how long you hold the shares, your tax basis is the purchase price plus whatever amount of income you recognized. Depending on when you purchased the stock and how your broker is reporting the compensation part of your tax basis on the revised Form 1099-B, the cost basis listed on that form may be incorrect or blank (see another article for the reason and how to handle the related tax reporting on Form 8949).

For sales of stock from ESPPs that are not tax-qualified under IRC Section 423, the taxation, along with the potential reporting mistakes, is similar to that for NQSOs. For all types of ESPP, see the section ESPPs: Taxes Advanced for details and examples, including a helpful FAQ on a range of ESPP tax-return mistakes.

Alert: For ESPPs that are tax-qualified under Section 423, purchases in a given tax year are reported on Form 3922 early in the following year. The form helps you collect information for reporting sales of ESPP shares on your tax return. For details, see the related article elsewhere on this website.

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Mistake No. 8: Failing To Track Stock Splits

If you exercised ISOs and the stock split before you sold, you need to ensure that your tax professional knows how many shares you were granted compared with how many you got as a result of the stock split. Otherwise, your accountant may assume that you have a larger AMT preference than you actually do, and you'll end up paying more tax than you should. Splits also affect your tax basis (they are not a disqualifying disposition), whether they are from ISO or NQSO exercises, ESPP purchases, or restricted stock vesting.

Example: The stock you are holding had a basis of $100 per share. With a 2-for-1 split, you have twice as many shares, and your basis is now $50 per share.

Mistake No. 9: Not Writing Off Worthless Securities

If you worked for a business that went bust, don't forget to take a loss from completely worthless company stock you may own. For you to obtain the loss, the company must effectively be out of business, and you can't have any reasonable expectation of being able to sell your stock. If you purchased stock in such a company, your loss is equal to the amount you paid for your shares.

You report a worthless security on Form 8949 and Schedule D, and you must follow the rules on capital losses and carry-overs.

You report a worthless security on Form 8949 and Schedule D, and you must follow the rules on capital losses and carry-overs. For NQSOs, the value of the stock on the exercise date (i.e. exercise price plus income recognized on spread) represents your basis. Your proceeds, of course, are zero. You do not get to write off any income that you previously reported or taxes that you paid in acquiring the stock. The tax treatment is usually the same when securities fraud caused the stock to lose all or most of its value, as explained in an FAQ on that topic.

Worthless stock needs to be written off in the year it becomes worthless, and the sale date that you put on Form 8949 and Schedule D is the last day of the relevant tax year. Otherwise, you'll need to amend your tax return to use the writeoff. You have seven years to amend your return for worthless securities, not the usual three.

Mistake No. 10: Failing To Take Advantage Of Special Tax-Code Sections

It is easy to miss perfectly legal tax breaks, especially for people with options and founder's stock. Section 1202 and Section 1045 of the Internal Revenue Code are especially relevant for founders and employees with stock in startups. If your company is officially considered a qualified small business corporation under Section 1202, you can exclude the gain on the sale of your stock up to $10 million, or 10 times the adjusted basis of that stock, if you have held it for more than five years.

For qualified small business stock purchased since September 27, 2010, this could mean that 100% of the gains may be excluded from capital gains tax (0% rate) and omitted from the AMT calculation (before then, the excludable amount was 50%). After a series of extensions, the Protecting Americans from Tax Hikes (PATH) Act of 2015, enacted near the end of 2015, made permanent this special tax treatment for QSB stock acquired after September 27, 2010. A holder of qualified small business stock can, alternatively, roll over (tax-free) any gain into another qualified small business within 60 days of the sale.

However, be careful about any so-called tax shelters for option income. Often what looks too good to be true catches the attention of the IRS and could subject you to paying back taxes and penalties.

Mistake No. 11: Botching The Math And Forgetting About Capital-Loss Carry-Forwards

If you've managed to avoid these first 10 mistakes: congratulations. Most of the hard work is behind you. This next error is one that affects all taxpayers, particularly those who complete their tax returns manually. It may seem strange, but many blunders are purely mathematical. Look out for areas where it is especially easy to make mistakes:

  • Add and subtract properly, including any capital gains and losses that are netted on Schedule D
  • Compute percentages in the correct way
  • Look at the right line on the tax table when figuring the amount of tax owed

Remember to use any capital-loss carry-forwards from last year, first to reduce your capital gains and then up to $3,000 of ordinary income.

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Even if your return is prepared by a tax professional, spend a few extra moments to check it for slip-ups. Be sure to ask questions about anything that does not make sense to you.

Mistake No. 12: Mechanical Errors

Don't trip up on simple careless mistakes that can delay the processing of your tax return and subject you to IRS penalties. Even if your return is prepared by a tax professional, spend a few extra moments to check it for slip-ups. Be sure to ask questions about anything that does not make sense to you.

Tax software, and asking tax-reporting experts to review your return, can reduce many mistakes. The IRS says returns filed electronically have an error rate of less than 1% compared with a 20% error rate for manual filings. The IRS e-file and Free File services are regularly updated for changes in tax law. But even electronic filing won't catch things like transposed Social Security numbers (names on returns must match Social Security numbers in the database of the Social Security Administration).

Additional Points

  • Six-month filing extensions. For tax returns that are overly complex, or if you need extra time, the IRS has made it easier to get a six-month filing extension with Form 4868 (see a related FAQ; you still must pay any taxes you owe by the normal deadline). Even when you cannot pay what you owe, you may want to at least file, as the penalty for late filing is much bigger than the penalty for late payments.
  • Schedule D cannot be attached to Forms 1040EZ or 1040A. IRS forms 1040EZ and 1040A do not allow the attachment of Schedule D. If you sold stock during the tax year, you will need to file IRS Form 1040.
  • Beware of email scams. The IRS has issued warnings about email scams involving tax refunds. Refunds do not (as many of these scams suggest) require a separate IRS form. In fact, the IRS never sends taxpayers unsolicited email and does not ask them for detailed personal and financial information by email.
  • Refund status. On its website, the IRS has a tool that can give taxpayers information about the status of their refunds (Where's My Refund?). With electronically filed returns, information is available 72 hours after the IRS confirms receipt. If you file a paper return, information is available three or four weeks after submission.

Bruce Brumberg is the Editor-in-Chief of Lynnette Khalfani is the CEO of and formerly was a reporter for The Wall Street Journal and CNBC.