how do capital gains work if you don't know the original purchase price?
"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."
There are all sorts of topics in finance that take a lot of time to learn.  You have valuation (time value of money, capital asset pricing model, dividend discount model, etc.), financial statement analysis (ratio analysis, free cash flow &amp; discounted cash flow, etc.) , capital structure analysis(Modgliani &amp; Miller theories of capital structure, weighted average cost of capital, more CAPM, the likes), and portfolio management (asset allocation, security selection, integrates financial statement analysis + other fields like derivatives, fixed income, forex, and commodity markets) and all sorts.   My opinion of Investopedia is that there is a lot of wheat with the chaff.  I think articles/entries are just user-submitted and there are good gems in Investopedia but a lot of it only covers very basic concepts.  And you often don't know what you don't know, so you might come out with a weak understanding of something.    To begin, you need to understand TVM and why it works.  Time value of money is a critical concept of finance that I feel many people don't truly grasp and just understand you need some 'rate' to use for this formula.  Also, as a prereq, you should understand basics of accrual accounting (debits &amp; credits) and how the accounting system works.  Don't need to know things like asset retirement obligations, or anything fancy, just how accounting works and how things affect certain financial statements.  After that, I'd jump into CAPM and cost of capital.  Cost of capital is also a very misunderstood concept since schools often just give students the 'cost of capital' for math problems when in reality, it's not just an explicit number but more of a 'general feeling' in the environment.  Calculating cost of capital is actually often very tricky (market risk premium) and subjective, sometimes it's not (LIBOR based).    After that, you can build up on those basic concepts and start to do things like dividend discount models (basic theory underlying asset pricing models) and capital asset pricing models, which builds on the idea of cost of capital.    Then go into valuation.  Learn how to price equities, bonds, derivatives, etc.  For example, you have the dividend discount model with typical equities and perpetuities.  Fixed income has things like duration &amp; convexity to measure risk and analyze yield curves.  Derivatives, you have the Black-Scholes model and other 'derivatives' (heh) of that formula for calculating prices of options, futures, CDOs, etc.  Valuation is essentially taking the idea of TVM to the next logical step.  Then you can start delving into financial modelling.  Free cash flows, discounted cash flows, ratio analysis, pro forma projections.  Start small, use a structured problem that gives you some inputs and just do calculations.  Bonuses* would be ideas of capital structure (really not necessary for entry level positions) like the M&amp;M theorems on capital structure (debt vs equity), portfolio management (risk management, asset allocation, hedging, investment strategies like straddles, inverse floaters, etc), and knowledge of financial institutions and banking regulations (Basel accords, depository regulations, the Fed, etc.).    Once you gain an understanding of how this works, pick something out there and do a report on it.  Then you'll be left with a single 'word problem' that gives you nothing except a problem and tells you to find an answer.  You'll have to find all the inputs and give reasons why these inputs are sound and reasonable inputs for this analysis.    A big part that people don't understand about projections and analysis is that **inputs don't exist in plain sight**.  You have to make a lot of judgment calls when making these assumptions and it takes a lot of technical understanding to make a reasonable assumption--of which the results of your report highly depend on.  As a finance student, you get a taste for all of this.  I'm gonna say it's going to be hard to learn a lot of substantial info in 2 months, but I'm not exactly sure what big business expects out of their grunts.  You'll mostly be doing practical work like desk jockey business, data entry, and other labor-based jobs.  If you know what you're talking about, you can probably work up to something more specialized like underwriting or risk management or something else.   Source:  Finance degree but currently working towards starting a (finance related) company to draw on my programming background as well. In a comment on this answer you asked  It's not clear to me why the ability to defer the gains would matter (since you never materially benefit until you actually sell) but the estate step up in basis is a great point! Could you describe a hypothetical exploitive scenario (utilizing a wash sale) in a little more detail?  This sounds like you still have the same question as originally, so I'll take a stab at answering with an example.   I sell some security for a $10,000 profit.  I then sell another security at a $10,000 loss and immediately rebuy.  So pay no taxes (without the rule).  Assuming a 15% rate, that's $1500 in savings which I realize immediately.  Next year, I sell that same security for a $20,000 profit over the $10,000 loss basis (so a $10,000 profit over my original purchase).  I sell and buy another security to pay no taxes.  In fact, I pay no taxes like this for fifty years as I live off my investments (and a pension or social security that uses up my tax deductions).  Then I die.  All my securities step up in basis to their current market value.  So I completely evade taxes on $500,000 in profits.  That's $75,000 in tax savings to make my heirs richer.  And they're already getting at least $500,000 worth of securities.   Especially consider the case where I sell a privately held security to a private buyer who then sells me back the same shares at the same price.   Don't think that $10,000 is enough?  Remember that you also get the original value.  But this also scales.  It could be $100,000 in gains as well, for $750,000 in tax savings over the fifty years.  That's at least $5 million of securities.   The effective result of this would be to make a 0% tax on capital gains for many rich people.   Worse, a poorer person can't do the same thing.  You need to have many investments to take advantage of this.  If a relatively poor person with two $500 investments tried this, that person would lose all the benefit in trading fees.  And of course such a person would run out of investments quickly.   Really poor people have $0 in investments, so this is totally impractical. There is no way you can directly defer that capital gains tax. If you sell a property that is not your principal residence, it will be taxed in the year in which it was sold. It doesn't matter what you do with the proceeds - that tax will get paid. Now, if you had adequate RRSP contribution room you could certainly put some money there, and would get a deduction on your tax return that would offset this capital gains tax. For example, if you sold a property for $300K that was originally purchased for $200K, then you would incur capital gains tax of $50K (assuming you were not claiming CCA deductions). If you took $50K of your proceeds and put it in an RRSP, it would offset the tax you pay now, and essentially defer the tax on that $50K of income until you withdraw - hopefully at a lower marginal tax rate. A spousal RRSP would work the same, except it would be taxed at your spouse's marginal tax rate when withdrawn. Either way, you need to have sufficient contribution room in the RRSP for this to work. Check your Notice of Assessment to see how much room you have available. "First, my economics professor would kill me if I didn't point out that lowering the price doesn't change **demand,** only **quantity demanded.** There's a pretty big difference between the two.  Anyway, the answer to your question is...it depends.  You're hoping that people who don't buy your sandwich for the original price will start buying it at the lower price. You're also hoping that once you increase the price they'll continue to buy it. The relationship describing how much a change in price affects the quantity demanded is known as elasticity. Elastic demand means that small changes will have a big affect on buying decisions. Inelastic demand means that buyers are not very flexible and will continue to purchase even after a significant price increase. Theoretically, at least.  The decision to raise or lower a price is a very complex process with a lot of variables, so I don't think anyone can give you a ""right answer"" to your question.  Practically, you need to figure out where these extra customers are coming from. If they aren't buying your sandwiches now because there's a cheaper alternative, lowering the price might entice them to buy from you instead. However, this means that when you raise the price back, they'll likely leave again.  If they don't know about your deli or haven't tried your sandwiches yet, a change in price isn't likely to do any good without a strong marketing campaign to back it up.  The uniqueness of your product could also have an effect. If your product is subway quality at higher prices, no one is going to stick around. On the other hand, if you lace your sandwiches with crack, you might get some repeat customers. Long-term loyalty is key ;)  Hopefully this rambling helps you. It's late and I need to sleep. Good luck!" Capital gain distribution is not capital gain on sale of stock. If you have stock sales (Schedule D) you should be filing 1040, not 1040A. Capital gain distributions are distributions from mutual funds/ETFs that are attributed to capital gains of the funds (you may not have actually received the distribution, but you still may have gain attributed to you). It is reported on 1099-DIV, and if it is 0 - then you don't have any. If you sold a stock, your broker should have given you 1099-B (which is not the same as 1099-DIV, but may be consolidated by your broker into one large PDF and not provided separately). On 1099-B the sales proceeds are recorded, and if you purchased the stock after 2011 - the cost basis is also recorded. The difference between the proceeds and the cost basis is your gain (or loss, if it is negative). Fees are added to cost basis. If a deal is struck, you're part of that deal because you own shares.  If someone offers $10/share for the entire company, you'll get that.  If the stock price is $1.50 and someone offers $2/share, you'll get that. Let's suppose your friend gave your $100 and you invested all of it (plus your own money, $500) into one stock. Therefore, the total investment becomes $100 + $500 = $600. After few months, when you want to sell the stock or give back the money to your friend, check the percentage of profit/loss. So, let's assume you get 10% return on total investment of $600.  Now, you have two choices. Either you exit the stock entirely, OR you just sell his portion. If you want to exit, sell everything and go home with $600 + 10% of 600 = $660. Out of $660, give you friend his initial capital + 10% of initial capital. Therefore, your friend will get $100 + 10% of $100 = $110. If you choose the later, to sell his portion, then you'll need to work everything opposite. Take his initial capital and add 10% of initial capital to it; which is $100 + 10% of $100 = $110. Sell the stocks that would be worth equivalent to that money and that's it. Similarly, you can apply the same logic if you broke his $100 into parts. Do the maths. If you were a business, all your assets would have a dollar value, so when you sold them you'd decrease the amount of assets by that amount and increase in cash, and if there was a profit on the sale it would go in as income, if there was loss it would count as a cost (or a loss)... so if there was a profit it would increase Equity, a loss then it would decrease Equity.  Since it's not really worthwhile doing a estimated cost for everything that you have, I'd just report it as income like you are doing and let the amount of equity increase proportionately. So, implicitly you always had roughly that amount of equity, but some of it was in the form of assets, and now you're liquidating those assets so the amount shows up in GnuCash. When you buy new things you might sell later, you could consider adding them as assets to keep track of this explicitly (but even then you have problems-- the price of things changes with time and you might not want to keep up with those price changes, it's a lot of extra work for a family budget) -- for stuff you already have it's better to treat things as you are doing and just treat the money as income-- it's easier and doesn't really change anything-- you always had that in equity, some of it was just off the books and now you are bringing it into the books.