Should I file a change of address with the IRS?
The most important thing to do when moving is to change your address with the post office. This will forward most mail for a year, and even automatically send change of address notices to many businesses that send mail to you. If you do this, and the IRS needs to send you something over the next year, you'll get it.  The IRS does have a procedure for changing your address, and you would want to do this if you are expecting something from the IRS and are unable to do a change of address with the post office for some reason. But if you do forward your mail and you aren't expecting a refund check, I don't think it is necessary. The IRS will get your new address when you file your return next year.
Per IRS regulations, if your stipend is not paying you for qualified expenses (primarily, tuition and books; explicitly not room and board or travel), it is taxable.  It doesn't require self-employment taxes (which are Medicare and FICA, normally paid in part by an employer), but it is taxable income from an income tax perspective.  You can generally deduct your books and such if you have your receipts - expenses 'required' by the institution for the coursework.  Do verify that the amount on the 1099-MISC reflects what you actually received in cash above and beyond the tuition waiver - don't assume the college did this the way you expect, or even properly.  Your bank statements should match the amount on the form. You should definitely include it in your gross income and pay taxes on it.  If you received alternate instruction, you should clarify that with the people doing the filing, and follow up with a supervisor perhaps (it's possible the volunteers helping at an event like this aren't familiar with this part of tax preparation). (Source, in addition to IRS regulations - I was my wife's tax preparer many of the years she was in her Ph.D. program.) "There are two different issues that you need to consider: and The answers to these two questions are not always the same.  The answer to the first is described in some detail in Publication 17 available on the IRS website. In the absence of any details about your situation other than what is in your question (e.g. is either salary from self-employment wages that you or your spouse is paying you,  are you or your spouse eligible to be claimed as a dependent by someone else, are you an alien, etc),  which of the various rule(s) apply to you cannot be determined, and so I will not state a specific number or confirm that what you assert in your question is correct.  Furthermore, even if you are not required to file an income-tax return, you might want to choose to file a tax return anyway. The most common reason for this is that if your employer withheld  income tax from your salary (and sent it to the IRS on your behalf) but your tax liability for the year is zero, then, in the absence of a filed tax return, the IRS will not refund the tax withheld to you. Nor will your employer return the  withheld money to you saying ""Oops, we made a mistake last year"".  That money is gone: an unacknowledged (and non-tax-deductible) gift  from you to the US government. So, while ""I am not required to file an income tax return and I refuse to do voluntarily what I am not  required to do""  is a very principled stand to take, it can have monetary consequences. Another reason to file a tax return even when one is not required to do so is to claim the Earned Income Tax Credit (EITC) if you qualify for it. As Publication 17 says in Chapter 36, qualified persons must File a tax return, even if you:   (a) Do not owe any tax,   (b) Did not earn enough money to file a return,   or   (c) Did not have income taxes withheld from your pay. in order to claim the credit. In short, read Publication 17 for yourself, and decide whether you are required to file an income tax return, and if you are not, whether it is worth your while to file the tax return anyway. Note to readers preparing to down-vote: this answer is prolix and says things that are far too ""well-known to everybody"" (and especially to you), but please remember that they might not be quite so well-known to the OP." "If she reported the income on the business return, I'd treat this as a ""mail audit"". Try to get a clear statement from Square confirming what they reported, under which SSN/EIN, for what transactions. Make a copy of that. If at all possible, get them to send a letter to the IRS (copy to you) acknowledging that they reported it under the wrong number. Copy the IRS's letter. Square's letter, and both personal and business 2012 returns. Write a (signed) cover letter explaining what had happened and pointing out the specific line in the business return which corresponded to the disputed amount, so they can see that you did report it properly and did pay taxes on it as business income. End that letter with a request for advice on how to straighten this out.  Certified-mail the whole package back to the IRS at whatever address the advisory letter gives. At worst, I'm guessing, they'll tell you to refile both returns for 2012 with that income moved over from the business return to the personal return, which will make everything match their records. But with all of this documentation in one place, they may be able to simply accept that Square misreported it and correct their files. Good luck. The IRS really isn't as unreasonable as people claim; if you can clearly document that you were trying to do the right thing, they try not to penalize folks unnecessarily." "Form W-9 (officially, the ""Request for Taxpayer Identification Number and Certification"") is used in the United States income tax system by a third party who must file an information return with the Internal Revenue Service (IRS). It requests the name, address, and taxpayer identification information of a taxpayer (in the form of a Social Security Number or Employer Identification Number). A W-9 is typically required when an individual is doing work, as a contractor or as an employee, for a company and will be paid more than $600 in a tax-year.  The company is required to file a W-2 or a 1099 and so requests a W-9 to get the information necessary for those forms. I cannot say if it is incompetence on the part of the accounting department or a deliberate ploy to make the refund process more onerous, but do not comply.  Politely nsist on a refund without any further information.  If the company refuses, request a charge-back from the credit-card company, file a complaint with the consumer-protection department of the state where the company is located, and write a bad review on Yelp or wherever else seems appropriate." With a $40,000 payment there is a 100% chance that the owner will be claiming this as a business expense on their taxes.  The IRS and the state will definitely know about it, and the risk of interest and penalties if it is not claimed as income make the best course of action to see a tax adviser. Because taxes will not be taken out by the property owner, the tax payer should also make sure that the estimated $10,000 in federal taxes, if they are in the 25% tax bracket, doesn't trigger other tax issues that could result in penalties, or the need to file quarterly taxes next year. This kind of extra income could also result in a change or an elimination of a health care subsidy. A unexpected mid-year  change could trigger the need to refund the subsidy received this year via the tax form next April. They will not send a bill, though there's a chance they will eventually send an accusatory letter.  You must proactively pay your taxes. The simplest route is to send a check to each taxing authority with the respective full amounts due.  I wouldn't bother calling them.  You could also file amended returns with each containing the correct information.  As a general rule, tax advisors tend to counsel against giving bank account information to the IRS for payment purposes (as opposed to refund purposes), both to protect the timing of payment and to make it slightly more difficult for them to seize or lien your account. If you choose to send a check, you can use Form 1040-V and NY Form IT-201-V.  Please triple check your Social Security Number matches your tax return SSN, so they correctly credit you for payment.  You may include an explanation of the closed account if you are feeling either fearful or contrite, but if the amount due is paid in full, then neither taxing authority should really care about your error. You're asking three different questions...  Q1: What's to stop people not reporting income earned in this manner?  A: Nothing. Absolutely nothing. The IRS doesn't have the means to keep track of your cash flow and your reported taxes on the fly.  Q2: How could the IRS possibly keep track of that? A: When you get audited. If it ever did come up that things didn't balance you would end up owing back taxes, with interest and possibly fines.  Q3: Moral obligations aside... why report? A: Since you've dismissed 'doing your duty as a citizen' as a moral obligation, the only other real one is that it's a pain in the butt to get audited and it is expensive if you lie and get caught. Form 1127 (updated link) should be filed in paper (with the supporting documents) to the IRS office that has jurisdiction in the area where you live. From the instructions (see the link above):  File Form 1127 with the Internal Revenue Service (Attn: Advisory Group   Manager), for the area where you maintain your legal residence or   principal place of business. See Pub. 4235, Collection Advisory Group   Addresses, to find the address for your local advisory group. However, if the tax due is a gift tax reportable on Form 709, send Form 1127   to: Department of the Treasury Internal Revenue Service Center Cincinnati, OH 45999