<prompt> Human: I received a letter from the IRS asking for 24,000. 18,000 in tax on underreported income, 1000 interest, and 4000 penalty. I dont think they are correct, but Im not sure. Need help understanding if they are indeed wrong, and then what steps to take to clear this up with them ASAP.Details:In late 2014, I sold about 47,000 in restricted stock shares that had vested between 2012 and early 2014. The sale was reported as wages on my W-2 and thusly reported on my return as wages. I was issued a 1099 but I didnt receive it because I moved in early 2015 and didnt think to check with the broker since it was all listed on my payslips and W-2. I was also used to stock options, not RSU, and the options did not trigger a 1099.Obviously, I screwed up on the 1099 issue. I have it now, and can report the stock sale of 47,000. The cost basis is listed as well, at about 32,000. Some of it is long term 20122013 best, some of it is short term early 2014 vest. I paid taxes at vesting each time. So I would only owe tax on the 15,000 difference? And would I even owe them anything on THAT, since I listed all of this as wagescomp on my W2 and return? Ive already paid that tax, right? Did I, in fact, overpay?Anyway, beyond figuring out exactly what I owenot owe, what do I do with the IRS? Just send them a letter?I did bring all of this to a tax pro in 2015, but I think he followed along with my assumption that since it was all on my W-2, I wasnt getting a 1099.  <response>: I would take all of this to a qualified CPA or a tax attorney and get it straightened out. Theyll be able to give you a more comprehensive look at whats going on to make sure nothing is missed. 