How to Calculate a Cost Basis For Your Stock (2024)

You bought General Electric shares in 1995 and sold the position last year. Now you’re filling out a Schedule D on your tax return and you realize that you have no idea what you did with your brokerage confirmations from 1995. What do you put down as the cost?

If you are flustered by missing paperwork, take heart. There are ways to reconstruct purchase prices, and I will outline some of them below.

For newly purchased shares, help is on the way. Congress has mandated that brokers keep purchase data on hand for any stocks bought in 2011 or later. Funds (exchange traded and mutual) will be covered beginning next year. Mandatory bond tracking begins in 2013.

All this may lessen your paperwork headaches down the road, but understand that the purpose of the legislation was not to improve your health. The IRS suspects that taxpayers reporting securities sales have a habit of overstating their purchase costs. The data on costs will be provided to tax collectors as well as to the taxpayers.

Long before these mandates came down, the brokerage industry began tracking cost basis, for a different purpose. By displaying unrealized gains and losses your broker can help you cut your tax bill. You let winners ride and you harvest losses for the tax deductions. More on harvesting here.

Charles Schwab & Co. has been showing its customers their purchase costs since 2005, and has retrofitted the database with trades going back to 1993. If you bought GE at Schwab in 1995 and still hold it there, you know what your cost was.

Fidelity Investments has been tracking costs for brokerage customers since 2000 and has backfilled data going back to 1988.

Both of these firms give you a tax optimizer for use when you have accumulated a position over time and now want to sell just a portion of it. Usually what you want to do is specify that the highest-cost shares are the ones you’re selling. That lowers your gain, or increases your loss deduction, as the case may be.

What about the really old trades? There are services that can track down old prices and make all the necessary splits and other adjustments. One of these is Netbasis, offered by the Phoenix, Ariz. firm NetWorth Services.

Your grandmother, let us fantasize, picked up 100 shares of Coca-Cola in January 1927. She sat on them as the shares split on more than one occasion and eventually gave the wad to you. You can’t put your hands on her brokerage ticket from 84 years ago. Now you’re thinking of selling. What’s the tax?

The meticulous report from Netbasis includes such fine points as the fractional share of Columbia Pictures you picked up along the way, and the 21-cent capital gain you would have had on that share when it was cashed out in 1988.

But the big money is in the co*ke. Before you sell, you’d want to take note of the unrealized gain on Granny’s round lot, which Netbasis duly reports as $53 million.

I took a quick tour of the Netbasis data set and came away impressed with its breadth. Several holes that I cited in an earlier version of this post have been filled.

Nico Willis, the 46-year-old former stockbroker who founded NetWorth in 1997, has a patent on basis adjustment algorithms. His Web site boasts that Netbasis data was used in a seminal 2005 study by the IRS of basis chiseling. (Say, wouldn’t it be nice if he were strictly on our side?)

Those algorithms pay off particularly well in reorganizations. Anyone who had a stake in the pre-1984 AT&T and still owns some or all of the pieces has a basis allocation nightmare on his hands. Netbasis takes care of it.

If you are missing a cost figure and the amount at stake is large, the $15 discounted fee for a report from Netbasis may be a good investment. Another option: buy a premium version of H&R Block At Home, which will give you unlimited access to the price database.

But before you buy any software, and certainly before you sell any stocks, contemplate all these ways of contending with cost basis:

If you have a gain, hang in there. You don’t owe tax until you sell, so don’t sell unless there’s a compelling reason. And if you never sell, you never have to tell the IRS what your cost was.

Remember that appreciation gets a permanent reprieve from income tax when the security in question is either given to charity or left in an estate. The latter phenomenon is known as step-up. If you haven’t heard of that, take a side trip to this primer on capital gains and losses.

See if it matters. No sense sweating over whether your cost was $2 a share or $3 if you only own 100 shares. In some cases you can just put $0 down as the cost—the IRS can’t object to that—and suffer no consequences.

Couples filing joint returns with taxable income below $68,000 get a 0% rate on long-term gains. Kids can have up to $1,900 of investment income before that income gets taxed at parental rates. If you have a $1,500 stock position of unknown cost that you want to get rid of, give it to your four-year-old and ask her if she’s interested in selling it.

Go to a library. Many big city libraries can give you free access to an archive like ProQuest, which has electronic copies of old Wall Street Journals, which have stock tables.

Check the Investor Relations department. Most public companies have a Web section with this rubric. It may have all the split history or other adjustments you need to reconstruct a basis.

Example: Aunt Mildred bought shares of Standard Oil (N.J.) on April 1, 1960 and later gave them to you. You now have 1,600 shares of Exxon Mobil. The Exxon Web site tells you about splits totaling 32-for-1 in the interim. So Mildred must have bought 50 shares. You fetch the old price of $41.50. Your cost basis is $2,075 plus her brokerage commission.

Why is Mildred’s basis your basis? Revisit that primer.

Construct an archive. If you still have positions dating to pre-electronic days, paw through your old brokerage statements while you can still find them and put the confirms in a safe place.

Backfill. If your brokerage statement makes note of “missing” costs, supply them. The data will help you trade intelligently and will speed up tax return preparation.

Customer-supplied cost data is not sent to the IRS and is of no probative value; you’ll still need documentation if you get challenged in an audit.

Capture data before switching brokers. The new broker will pick up your assets but not purchase prices before 2011. Download cost data before moving.

If you must, estimate. Suppose you know you bought Norfolk & Western in 1981 but you don’t know exactly when. It would be safe to use the low for the year as your cost. You might be able to pinpoint a year but not a date if, for example, you have old tax records that show railroad dividends in 1981 but not 1980.

Be careful with bonds. They can get kinky.

Example 1: A company gets into trouble and you buy $100,000 of its bonds for $92,000. The bonds pay off at par. The cost basis that goes on Schedule D is not $92,000 but $100,000. The $8,000 gain is “interest income.” Totally unfair, but don’t get me started.

Example 2: You buy an inflation-protected bond for $100,000. The inflation adjustment raises your principal amount to $103,000. You pay tax on $3,000 of mythical interest. You sell the thing for $104,000. Fidelity accurately reports your capital gain as $1,000. Brokers with outdated software tell you the capital gain is $4,000. For bonds bought after Jan. 1, 2013, though, all brokers should report accurate adjusted costs.

Note: I own or owned some of the securities mentioned in this article.

How to Calculate a Cost Basis For Your Stock (2024)

FAQs

How to Calculate a Cost Basis For Your Stock? ›

When you buy stocks, for example, you typically calculate the initial cost basis by adding commissions and fees to the per-share purchase price.

How do you calculate cost basis of a stock? ›

You can calculate your cost basis per share in two ways: Take the original investment amount ($10,000) and divide it by the new number of shares you hold (2,000 shares) to arrive at the new per-share cost basis ($10,000/2,000 = $5).

How do you determine the cost basis of a stock option? ›

For stocks and bonds, the cost basis is generally your purchase price for the securities, including reinvested dividends or reinvested capital gains distributions, plus additional costs such as the commission or other fees you paid to complete the transaction.

How do you find the unknown cost basis of a stock? ›

If you know when the stock was purchased, here are some tips:
  1. Sign in to your brokerage account. ...
  2. Look at previous broker statements. ...
  3. Contact your brokerage firm. ...
  4. Go online for historical stock prices. ...
  5. Go directly to the source.
Dec 14, 2023

How does IRS verify cost basis? ›

Purchase Records

If you purchased the asset, documents from the original sale are the preferred option for verifying cost basis. This can include any brokerage statements, commission statements or other proof of purchase for securities that you purchased.

What is the best cost basis method? ›

First-in, first-out method (FIFO)

This is the default for all investments other than mutual funds. Method implications: Because asset prices tend to rise over time, using FIFO as your cost basis method will have the oldest shares sold first, and those shares will often have the lowest cost basis.

What is the formula for average cost basis? ›

Cost basis represents the initial value of a security or mutual fund that an investor owns. The average cost is calculated by dividing the total amount in dollars invested in a mutual fund position by the number of shares owned.

What is an example of a cost basis? ›

Typically, when you purchase shares of stock, the cost basis is simply the price you paid for each share. Say you purchased 10 shares of XYZ for $100 per share in a taxable brokerage account. The total cost would be $1,000, and your cost basis for each individual share would be $100.

What is the cost basis for awarded stock? ›

Cost basis is the price paid to acquire shares plus commissions and any fees. Stock plans enable employers to issue company stock for services rendered. Employers issue company stock as part of compensation to their employees.

What happens if 1099-B does not show cost basis? ›

How can we help? The Form 1099-B that you receive might only report the sale date and sales proceeds. If it does not report the date acquired or cost basis, you still need to enter that information when you report your Form 1099-B in the TaxAct program so that it will transfer to Schedule D and/or Form 8949.

How do you fix missing cost basis? ›

How Do I Fix a First Inflow Missing Basis Warning?
  1. Edit the flagged Deposit or Uncategorized transaction and change the classification to a different transaction type that assigns cost basis. ​
  2. Import additional data that shows how the asset was acquired.

Can you sell stock without cost basis? ›

If you sell an investment such as a stock or mutual fund, the IRS requires that you report any capital gains or losses along with cost basis information.

What is the original cost basis of a stock? ›

For stocks or bonds, the cost basis is generally the price you paid to purchase the securities, including purchases made by reinvestment of dividends or capital gains distributions, plus other costs such as the commission or other fees you may have paid to complete the transaction.

What if I can't determine cost basis? ›

You can Go online for historical stock prices For example, the historical section at Marketwatch or Nasdaq. It's generally acceptable to take the lowest and highest price from a given day and average them to arrive at a cost basis.

How to calculate cost base? ›

The cost base of your asset is the total of:
  1. what your asset cost you.
  2. certain incidental costs of buying and selling it – brokerage or agent's fees, legal fees, stamp duty and investment advisers' fees (but not investment seminar costs)
Feb 15, 2024

How do you calculate the tax basis? ›

For most business assets, calculating tax basis starts with the original cost of the asset, including any purchase costs, such as sales commissions and shipping fees. Then adjustments are added or subtracted. For example, depreciation reduces an asset's tax basis while capital improvements increase it.

Does return of capital reduce cost basis? ›

RoC typically is not taxed in the current year. Instead, it reduces a shareholder's cost basis in the fund. When the shareholder sells his or her fund shares, any gains will consider the selling price relative to the reduced cost basis. This means that RoC may defer some of the shareholder's tax liability.

How do you calculate cost base of shares sold? ›

The cost base of your asset is the total of:
  1. what your asset cost you.
  2. certain incidental costs of buying and selling it – brokerage or agent's fees, legal fees, stamp duty and investment advisers' fees (but not investment seminar costs)
Feb 15, 2024

What is the difference between cost basis and market value? ›

Market value is the current worth of an asset or security, determined by its supply and demand in the marketplace. Cost basis, on the other hand, is the original price at which you purchased an asset or security.

What is the difference between cost basis and balance? ›

Cost basis refers to the total amount paid for a product or service, while balance refers to the outstanding amount owed on that product or service. It's important to keep track of both these figures as they provide valuable insights into your company's financial health.

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