Stock grant, taxes, and the IRS
I went through this too. There's a safe-harbor provision. If you prepay as estimated tax payments, 110% of your previous year's tax liability, there's no penalty for underpayment of the big liquidity-event tax liability.  https://www.irs.gov/publications/p17/ch04.html That's with the feds. Your state may have different rules. You would be very wise indeed to hire an accountant to prepare your return this year. If I were you I'd ask your company's CFO or finance chief to suggest somebody.   Congratulations, by the way. If you have a one-time event, you are allowed to make a single estimated payment for that quarter on Form 1040-ES.  People seem to fear that if they make one such payment they will need to do it forevermore, and that is not true.  The IRS instructions do kind of read that way, but that's because most people who make estimated payment do so because of some repeating circumstance like being self-employed. In addition, you may qualify for one or more waivers on a potential underpayment penalty when you file your Form 1040 even if you don't make an estimated payment, and you may reduce or eliminate any penalty by annualizing your income - which is to say breaking it down by quarter rather than the full year.  Check on the instructions for Form 2210 for more detail, including Schedule AI for annualizing income.  This is some work, but it might be worthwhile depending on your situation. https://www.irs.gov/instructions/i2210/ch02.html
"The only ""authoritative document"" issued by the IRS to date relating to Cryptocurrencies is Notice 2014-21. It has this to say as the first Q&A: Q-1: How is virtual currency treated for federal tax purposes?   A-1: For federal tax purposes, virtual currency is treated as property. General tax principles applicable to property transactions apply to transactions using virtual currency. That is to say, it should be treated as property like any other asset. Basis reporting the same as any other property would apply, as described in IRS documentation like Publication 550, Investment Income and Expenses and Publication 551, Basis of Assets. You should be able to use the same basis tracking method as you would use for any other capital asset like stocks or bonds. Per Publication 550 ""How To Figure Gain or Loss"", You figure gain or loss on a sale or trade of property by comparing the amount you realize with the adjusted basis of the property. Gain. If the amount you realize from a sale or trade is more than the adjusted basis of the property you transfer, the difference is a gain. Loss. If the adjusted basis of the property you transfer is more than the amount you realize, the difference is a loss.  That is, the assumption with property is that you would be using specific identification. There are specific rules for mutual funds to allow for using average cost or defaulting to FIFO, but for general ""property"", including individual stocks and bonds, there is just Specific Identification or FIFO (and FIFO is just making an assumption about what you're choosing to sell first in the absence of any further information). You don't need to track exactly ""which Bitcoin"" was sold in terms of exactly how the transactions are on the Bitcoin ledger, it's just that you bought x bitcoins on date d, and when you sell a lot of up to x bitcoins you specify in your own records that the sale was of those specific bitcoins that you bought on date d and report it on your tax forms accordingly and keep track of how much of that lot is remaining. It works just like with stocks, where once you buy a share of XYZ Corp on one date and two shares on another date, you don't need to track the movement of stock certificates and ensure that you sell that exact certificate, you just identify which purchase lot is being sold at the time of sale." Vesting typically stops after you quit.   So, if your plan vests 20% per year for 5 years, and you received a one-time stock grant as part of this plan (i.e., ignoring the fact that these often involve new grants each year that vest separately), and you were hired in 2014 and leave at the end of 2016, then you vested 20% in 2015 and 20% in 2016, so would have 40% of the stock vested when you quit, and would never have more than that. I can make that election to pay taxes now (even though they aren't vested) based on the dollar value at the time they are granted? That is correct. You must file the election with the IRS within 30 days after the grant (and then attach a copy to that year's tax return). would I not pay any taxes on the gains because I already claimed them as income? No, you claim income based on the grant value, the gains after that are your taxable capital gains. The difference is that if you don't use 83(b) election - that would not be capital gains, but rather ordinary salary income. what happens if I quit / get terminated after paying taxes on un-vested shares? Do I lose those taxes, or do I get it back in a refund next year? Or would it be a deduction next year? You lose these taxes. That's the risk you're taking. Generally 83(b) election is not very useful for RSUs of established public companies. You take a large risk of forfeited taxes to save the difference between capital gains and ordinary gains, which is not all that much. It is very useful when you're in a startup with valuations growing rapidly but stocks not yet publicly trading, which means that if you pay tax on vest you'll pay much more and won't have stocks to sell to cover for that, while the amounts you put at risk are relatively small. "No, you cannot. ISO are given to you in your capacity as an employee (that's why it is ""qualified""), while your IRA is not an employee. You cannot transfer property to the IRA, so you cannot transfer them to the IRA once you paid for them as well. This is different from non-qualified stock options (discussed in this question), which I believe technically can be granted to IRA. But as Joe suggests in his answer there - there may be self-dealing issues and you better talk to a licensed tax adviser (EA/CPA licensed in your State) if this is something you're considering to do." I assume US as mhoran_psprep edited, although I'm not sure IRS necessarily means US. (It definitely used to also include Britain's Inland Revenue, but they changed.)  (US) Stockbrokers do not normally withhold on either dividends/interest/distributions or realized capital gains, especially since gains might be reduced or eliminated by later losses. (They can be required to apply backup withholding to dividends and interest; don't ask how I know :-) You are normally required to pay most of your tax during the year, defined as within 10% or $1000 whichever is more, by withholding and/or estimated payments. Thus if the tax on your income including your recent gain will exceed your withholding by 10% and $1000, you should either adjust your withholding or make an estimated payment or some combination, although even if you have a job the last week of December is too late for you to adjust withholding significantly, or even to make a timely estimated payment if 'earlier in the year' means in an earlier quarter as defined for tax (Jan-Mar, Apr-May, June-Aug, Sept-Dec). See https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes and for details its link to Publication 505. But a 'safe harbor' may apply since you say this is your first time to have capital gains. If you did not owe any income tax for last year (and were a citizen or resident), or (except very high earners) if you did owe tax and your withholding plus estimated payments this year is enough to pay last year's tax, you are exempt from the Form 2210 penalty and you have until the filing deadline (normally April 15 but this year April 18 due to weekend and holiday) to pay. The latter is likely if your job and therefore payroll income and withholding this year was the same or nearly the same as last year and there was no other big change other than the new capital gain. Also note that gains on investments held more than one year are classified as long-term and taxed at lower rates, which reduces the tax you will owe (all else equal) and thus the payments you need to make. But your wording 'bought and sold ... earlier this year' suggests your holding was not long-term, and short-term gains are taxed as 'ordinary' income. Added: if the state you live in has a state income tax similar considerations apply but to smaller amounts. TTBOMK all states tax capital gains (and other investment income, other than interest on exempt bonds), and don't necessarily give the lower rates for long-term gains. And all states I have lived in have 'must have withholding or estimated payments' rules generally similar to the Federal ones, though not identical. It really depends.  If it is offered as compensation (ie in leiu of, or in addition to salary or cash bonus) then it would be reportable income, and if sold later for a profit then that would be taxable as gains.  If this share is purchased as an investment at current value then it would be treated like other securities most likely gains realized at sale.  Any discount could be considered income but there are some goofy rules surrounding this enacted to prevent tax evasion and some to spur growth.  That is the answer in a nut shell.  It is far more complicated in reality as there are somewhere around 2000 pages of regulations deal with different exceptions and scenerios. If the IRS has your money (the withholding you mentioned), and you do not owe the IRS any/all of it, you have to file a return to get it back.  No return, no refund. Generally stock trades will require an additional Capital Gains and Losses form included with a 1040, known as Schedule D (summary) and Schedule D-1 (itemized).  That year I believe the maximum declarable Capital loss was $3000--the rest could carry over to future years. The purchase date/year only matters insofar as to rank the lot as short term or long term(a position held 365 days or longer), short term typically but depends on actual asset taxed then at 25%, long term 15%.  The year a position was closed(eg. sold) tells you which year's filing it belongs in. The tiny $16.08 interest earned probably goes into Schedule B, typically a short form. The IRS actually has a hotline 800-829-1040 (Individuals)  for quick questions such as advising which previous-year filing forms they'd expect from you.  Be sure to explain the custodial situation and that it all recently came to your awareness etc. Disclaimer: I am no specialist. You'd need to verify everything I wrote; it was just from personal experience with the IRS and taxes.