Why is RSU tax basis based on remaining shares after shares are witheld?
You only got 75 shares, so your basis is the fair market value of the stock as of the grant date times the number of shares you got: $20*75.  Functionally, it's the same thing as if your employer did this: As such, the basis in that stock is $1,500 ($20*75). The other 25 shares aren't yours and weren't ever yours, so they aren't part of your basis (for net issuance; if they were sell to cover, then the end result would be pretty similar, but there'd be another transaction involved, but we won't go there).  To put it another way, suppose your employer paid you a $2000 bonus, leaving you with a $1500 check after tax withholding. Being a prudent person and not wishing to blow your bonus on luxury goods, you invest that $1500 in a well-researched investment. You wouldn't doubt that your cost basis in that investment at $1500. Here is how it should look: 100 shares of restricted stock (RSU) vest. 25 shares sold to pay for taxes. W2 (and probably paycheck) shows your income going up by 100 shares worth and your taxes withheld going up by 25 shares worth. Now you own 75 shares with after-tax money. If you stop here, there would be no stock sale and no tax issues.  You'd have just earned W2 income and withheld taxes through your W2 job. Now, when you sell those 75 shares whether it is the same day or years later, the basis for those 75 shares is adjusted by the amount that went in to your W2.   So if they were bought for $20, your adjusted basis would be 75*$20.
Now, if I'm not mistaken, tracking a value-weighted index is extremely easy - just buy the shares in the exact amount they are in the index and wait. Yes in theory. In practise this is difficult. Most funds that track S&P do it on sample basis. This is to maintain the fund size. Although I don't have / know the exact number ... if one wants to replicate the 500 stocks in the same %, one would need close to billion in fund size. As funds are not this large, there are various strategies adopted, including sampling of companies [i.e. don't buy all]; select a set of companies that mimic the S&P behaviour, etc. All these strategies result in tracking errors. There are algorithms to reduce this. The only time you would need to rebalance your holdings is when there is a change in the index, i.e. a company is dropped and a new one is added, right? So essentially rebalance is done to; If so, why do passive ETFs require frequent rebalancing and generally lose to their benchmark index? lets take an Index with just 3 companies, with below price. The total Market cap is 1000  The Minimum required to mimic this index is 200 or Multiples of 200. If so you are fine.    More Often, funds can't be this large. For example approx 100 funds track the S&P Index. Together they hold around 8-10% of Market Cap. Few large funds like Vangaurd, etc may hold around 2%. But most of the 100+ S&P funds hold something in 0.1 to 0.5 range. So lets say a fund only has 100. To maintain same proportion it has to buy shares in fraction. But it can only buy shares in whole numbers. This would then force the fund manager to allocate out of proportion, some may remain cash, etc. As you can see below illustrative, there is a tracking error. The fund is not truly able to mimic the index.  Now lets say after 1st April, the share price moved, now this would mean more tracking error if no action is taken [block 2] ... and less tracking error if one share of company B is sold and one share of company C is purchased.  Again the above is a very simplified view. Tracking error computation is involved mathematics.  Now that we have the basic concepts, more often funds tracking S&P; Thus they need to rebalance. Cost basis is irrelevant because the entire distribution is taxed as ordinary income even if the custodian distributes stock or mutual fund shares to you. Such distributions save you the brokerage fees that you would incur had you taken a cash distribution and promptly bought the shares outside the retirement account for yourself but they have no effect on the tax treatment of the distribution: the market value of the shares distributed to you is taxed as ordinary income, and your basis in the newly acquired shares outside the retirement account is the market value of the shares, all prices being as of the date of the distribution. The shareholders have a claim on the profits, but they may prefer that claim to be exercised in ways other than dividend payments. For example, they may want the company to invest all of its profits in growth, or they may want it to buy back shares to increase the value of the remaining shares, especially since dividends are generally taxed as income while an increase in the share price is generally taxed as a capital gain, and capital gains are often taxed at a lower rate than income. The $50k is subject to the appropriate income taxes, which may include FICA taxes including the employer share if you are self employed. The after tax money can then be invested with the amount invested being the cost basis (I.e., if you invest $40k you will have a cost basis of $40k).  In future years you will have taxes due if any of those investments pay dividends (or capital gain distributions). Once you sell you will have a capital gain or loss that you will pay taxes on (or take a deduction if a loss). Now you can improve this picture if you are able to put some of your money into a retirement account (either a tax deductible or a ROTH). With retirement accounts you do not pay tax on the capital gains or dividends. If you use a tax deferred account your tax is higher but that is because you were also investing Uncle Sam's portion of your pay check. "There are two scenarios to determine the relevant date, and then a couple of options to determine the relevant price. If the stocks were purchased in your name from the start - then the relevant date is the date of the purchase. If the stocks were willed to you (i.e.: you inherited them), then the relevant date is the date at which the person who willed them to you had died. You can check with the company if they have records of the original purchase. If it was in ""street name"" - they may not have such records, and then you need to figure out what broker it was to hold them. Once you  figured out the relevant date, contact the company's ""investor relationships"" contact and ask them for the adjusted stock price on that date (adjusted for splits/mergers/acquisitions/whatever). That would be the cost basis per share you would be using. Alternatively you can research historical prices on your favorite financial information site (Google/Yahoo/Bloomberg or the stock exchange where the company is listed). If you cannot figure the cost basis, or it costs too much - you can just write cost basis as $0, and claim the whole proceeds as gains. You'll pay capital gains tax on the whole amount, but that may end up being cheaper than conducting the investigation to reveal the actual numbers." I don't understand the logic in the other answer, and I think it doesn't make sense, so here is my take: You pay taxes on income, not on sales price. So if you put X $ of your own money in the account and it becomes X + Y $ in the future, at the moment of liquidation, you will own taxes on the Y $. Never on the X $, as it was your own (already taxed) money to begin with. The difference between long-term and short-term gains just influences the tax rate on Y. If you donate the gain alone (the Y $) to charity, you can deduct Y from your tax base. So adding Y to your tax base and then deducting Y again obviously leaves your tax base at the old value, so you pay no extra taxes. Which seems logical, as you didn't make any money in the process. Aside from extreme cases where the deductible gain is too large a percentage from your income or negative, I don't see why this would ever be different. So you can take your original 100 $ back out and donate all gains, and be fine. Note that potential losses are seen different, as the IRA regulations are not symmetric. Now assume these shares are vested, held for at least 1 year, and are   then sold for $5 each. Everything I've read implies that the grantee   now owes long-term capital gains taxes on the difference, which would   be 10k * ($5 - $1). No. That's exactly what the SO is NQ for. Read more on the differences between ISO and NQSO here. Now assume these shares are vested, held for at least 1 year, and are   then sold for $5 each. Everything I've read implies that the grantee   now owes long-term capital gains taxes on the difference, which would   be 10k * ($5 - $1). At this point you no longer have NQSO, you have RSU. If you filed 83(b) when  you exercised, then you pay capital gains tax when they vest. If you didn't - its ordinary income to you. NQSO is a red herring here since once exercised they no longer exist. If you didn't file 83(b), then when the stock vests the difference between the FMV at vest and the money you spent on it when exercising (if any) is considered wages and taxed as ordinary income (+FICA etc). From that point the RSU becomes a regular stock investment and the capital gains clock starts ticking. "A nondividend distribution is typically a return of capital; in other words, you're getting money back that you've contributed previously (and thus would have been taxed upon in previous years when those funds were first remunerated to you). Nondividend distributions are nontaxable, so they do not represent income from capital gains, but do effect your cost basis when determining the capital gain/loss once that capital gain/loss is realized. As an example, publicly-traded real estate investment trusts (REITs) generally distribute a return of capital back to shareholders throughout the year as a nondividend distribution. This is a return of a portion of the shareholder's original capital investment, not a share of the REITs profits, so it is simply getting a portion of your original investment back, and thus, is not income being received (I like to refer to it as ""new income"" to differentiate). However, the return of capital does change the cost basis of the original investment, so if one were to then sell the shares of the REIT (in this example), the basis of the original investment has to be adjusted by the nondividend distributions received over the course of ownership (in other words, the cost basis will be reduced when the shares are sold). I'm wondering if the OP could give us some additional information about his/her S-Corp. What type of business is it? In the course of its business and trade activity, does it buy and sell securities (stocks, etc.)? Does it sell assets or business property? Does it own interests in other corporations or partnerships (sales of those interests are one form of capital gain). Long-term capital gains are taxed at rates lower than ordinary income, but the IRS has very specific rules as to what constitutes a capital gain (loss). I hate to answer a question with a question, but we need a little more information before we can weigh-in on whether you have actual capital gains or losses in the course of your S-Corporation trade."