Where I am I liable for taxes?
You will have to pay your taxes in the UK not USA. For tax purposes it is the company's tax residency not where the server is located. You are just hiring a server in USA. Take for example a CDN being used for your same service then would you pay taxes in 300 different countries if you use Akamai? Does not work that way.
"And you were criticizing me for making blanket, general statements...   Did you want to talk about something specific, or did you want to keep the discussion to the generalities like arguing about whether taxes are ""noble or ignoble""?   If it is the latter, than I get the gist of what you are saying, but disagree with you. And I say this from a position of paying a lot more in taxes than I am betting you do, so it is not from a position of rhetoric but actuality." It sounds like you do. You earn money in NC, so that's where it is going to be taxed first. According to the Colorado form CY104PN, Colorado taxes income earned while working in or being a resident of the State of Colorado. Assuming you never set foot in the State of Colorado, I read it as if you will only be liable to pay taxes in the State of New York (on all of your income, of course). You can get a more reliable opinion from a Colorado-licensed CPA. "You would put your earnings (and expenses, don't forget) on Schedule C, and then do a Schedule SE for self-employment tax. http://www.irs.gov/businesses/small/article/0,,id=98846,00.html 1040ES isn't used to compute taxes, it's used to pay taxes. Generally you are supposed to pay taxes as you go, rather than when you file. There are exceptions where you won't be penalized for paying when you file, ""most taxpayers will avoid this penalty if they owe less than $1,000 in tax after subtracting their withholdings and credits, or if they paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller"" from http://www.irs.gov/taxtopics/tc306.html  i.e. there's a safe harbor as long as you pay as much as you owed the year before. If you owe a lot at the end of the year a second time in a row, then you get penalized." There are ways to avoid having federal income taxes withheld:  In order to avoid withholding altogether, you’ll have to fall into   both of the following categories: you have no tax liability this year   and you had no tax liability in the previous tax season, so all of the   federal income tax you paid was given back to you. Generally, you can   say you have no tax liability when you’re not required to file an   income tax return or you owe zero taxes. You may also be able to claim   an exemption if your earned income for the year is extremely low   ($1,050 or less). If those conditions apply to you, you can write “exempt” in line 7.   Keep in mind that the exemption only eliminates your federal income   taxes, not your Medicare or Social Security. If your parents use an accountant to prepare their taxes, I'm sure he/she would be able to give you a solid answer on how to fill it out. Ultimately, you are the one that is responsible for your tax filings and your payments (It's all linked to your SSN, after all). If this fee/interest is the result of a filing error, and you went through a preparing company which assumes liability for their own errors, then you should speak to them. They will likely correct this and pay the fees.  On the other hand, if this is the result of not making quarterly payments, then you are responsible for it. (Source: Comptroller of Maryland Site) If you [...] do not have Maryland income taxes withheld by an employer, you can make quarterly estimated tax payments as part of a pay-as-you-go plan. If your employer does withhold Maryland taxes from your pay, you may still be required to make quarterly estimated income tax payments if you develop a tax liability that exceeds the amount withheld by your employer by more than $500. From this watered-down public-facing resource, it seems like you'll get hit with fees for not making quarterly payments if your tax liability exceeds $500 beyond what is withheld (currently: $0). "Finally, I got response from finance center:  ""It doesn't matter where do you study, what does matter is where you   live. So, once you live in Germany, you pay taxes in Germany. And   it doesn't matter who you work for."" So, there are two options to pay taxes: it's paid by an employer or an employee: If I would work for Swiss company, I need to show how much money I make every month (or year) to Finance Center." The instructions for Form W-7 include a table of exceptions to the requirement to attach a tax return.  It looks like you might fall under Exemption 2a, but I don't think there's quite enough information in your question to be sure. The current instructions are here: https://www.irs.gov/pub/irs-pdf/iw7.pdf The table of exceptions runs from page 7 to page 9, so I won't try to reproduce it here. So why not talk to your employer, and ask them to pay you in gold dust? Then when tax time comes, just convert some gold dust into the amount of USD in taxes you owe.   Of course, you'd have to find farmers and shoemakers and electronic stores willing to accept payment in gold dust as well... @gef05 He was making a reference to expatriation and renouncing citizenship. Citizens have to pay taxes wherever they are no matter how long they are there, people that renounce their citizenship have to continue paying income taxes to the US IRS for several years As a resident of New York State you will, in addition to the Federal income tax handled by the IRS, be responsible for state and local income taxes. For New York the state tax forms are also used to determine your New York city tax. If HR was either not aware of the local tax requirement for New York or you filled out the New York State version of the W-4 incorrectly you may have had too little tax withheld for New York state. The refund from the IRS is not dependent on the refund/owe status for state and local taxes. It is possible that your state taxes are fine but that you owe taxes to the city. That tax you owe to the city will reduce the refund from the state and may require you to pay money to New York. Of course if you do itemize, what you pay to the state and city may result in deductions on your federal form. If you owe back taxes to the state or local government this could result in the IRS seizing a federal refund, but that doesn't happen right away. For purposes of the EIN the address is largely inconsequential. The IRS cannot (read: won't) recover the EIN if you fail to write it down after the website generates it for you. On your actual tax form the address is more consequential, and this is more so a question of consistency than anything. But an entity can purchase property anywhere and have a different address subsequent years. Paying the actual taxes means more than the semantical inconsistencies. The whole purpose of separate accounts is to make an audit easier, so even if someone imagines that some action (such as address ambiguity) automatically triggers an audit, all your earnings/purchases are not intermingled with personal stuff, which just streamlines the audit process. Consequences (or lack thereof) aside, physical means where physical property is. So if you have an actual mailing address in your state, you should go with that. Obviously, this depends on what arrangement you have with your registered agent, if all addresses are in Wyoming then use the Wyoming address and let the Registered Agent forward all your mail to you. Don't forget your $50 annual report in Wyoming ;) How did you open a business paypal without an EIN? Business bank accounts? Hm... this is for liability purposes... It is not a question of where you have your driver's license.  It is a question of the states' tax related residency rules.  (Though a driver's license can be a part of that question.) Since you likely have a residence in NYC and so can prove residency through a lease, bills, etc., you probably have to file as a NYS/NYC resident.   I do have to question your maintaining a California driver's license if you are not a resident.  If you are attempting to maintain dual-residency, look into both states' residency rules to see if you are liable for taxes in both states.   California seems particularly picky about these types of situations, probably due to concerns that you may be trying to circumvent California taxes.  That said, it usually revolves around income in the state.  Of course, if you maintain residency in California as well, the argument can be made that you owe some taxes due to the fact that you take advantage of state services.  (E.g. you drive on California roads.) I suggest you consult a tax professional knowledgeable in these issues to sort out the details. Whether you're self-employed or not, knowing exactly how much tax you will pay is not always an easy task.  Various actions you can take (e.g., charitable donations, IRA contributions, selling stocks) may increase or reduce your tax liability. One tool I've found useful for estimating federal taxes is the Excel 1040 spreadsheet.  This is a spreadsheet version of the income tax return form.  It is not official and is not created by the IRS, but is maintained as a labor of love by a private individual.  In practice, however, it is pretty much an accurate implementation of the tax calculation algorithms encoded in the tax forms and instructions. The nice thing about it is that it's a spreadsheet.  You can plug numbers into various slots in the spreadsheet and see how they affect your federal tax liability.  (You may also owe state taxes depending on what state you live in.)  Of course, the estimates you get by doing this are only (at most) as accurate as your estimates of the various numbers you plug in.  Still, I think it's a free and useful way to get a ballpark estimate of your tax liability based on numbers that you can more easily estimate (e.g., how much money you expect to earn). I don't think the location of the funds is any of your concern. You're buying a CDI, which is: Australian financial instruments The US has no jurisdiction over you, being you an Australian, so unless you own a US-based asset (i.e.: a real-estate in the US, or a US brokerage account), US tax laws shouldn't matter to you.