How can I make a one-time income tax-prepayment to the US Treasury?
"You can make estimated tax payments on Form 1040-ES.  Most people who make such payments need to do it quarterly because the typical reasons for making estimated payments is something like self-employment income that a person will get throughout the year.  If you have a one-time event like a single, large sale of stock, however, there's nothing wrong with doing it just one quarter out of the year. When it comes time to file your taxes, part of the calculate is whether you were timely quarter-by-quarter not just for the entire year, so if you do have a big ""one-time"" event mid-year, don't wait until the end of the year to file an estimated payment.  Of course, if the event is at the end of the year, then you can make it a 4th quarter estimated payment."
"The can and the should have been discussed in other answers and comments,  and so I will discuss the how.  As others have noted, it is important to make sure that the additional money goes to reducing principal and not towards  prepayment of interest.  Unfortunately, very few bank tellers understand how mortgages work and very few bank officers - even loan officers - understand how mortgages work too. Thus a statement that you want the extra money to go towards principal will likely be met with a blank look. Furthermore, what they do with the money and how it is entered on the bank books that afternoon when the transactions are recorded may have no resemblance to what was discussed and agreed to earlier in the day.  Based on my personal experiences and  many arguments with banks about how they handled my prepayments and how interest was computed, I would  recommend the following (which is easier now that automated payments are possible for the standard monthly payment and additional payments are possible via electronic funds transfer). Make sure that automated payments are made on the day that the payment is due, not at the end of the ten-day grace period that banks love to grant you for making the monthly payment. Yes, there is no penalty for late payment as long as you pay before the end of the grace period, but interest continues to be charged and so more of each graciously delayed payment goes to interest  and less towards principal. Make the additional payment on the same day as the standard monthly mortgage payment is made. This ensures that at worst just one day's interest is owing when the additional payment is made. Also, payment in the middle of the monthly cycle is an almost sure way of getting ripped off on the interest because the bank's computers will post the payment in the manner most favorable to them, and usually contrary to the terms of your mortgage.  I have  complained to banks about mishandled mid-month payments and won every time, and on many occasions the bank officer would grudgingly say ""We have always done it this way and nobody  ever complained till you did today."" I doubt very much if the bank's programs got changed as a result of my complaints. If you are not sure how mortgages work and how interest  is calculated or don't have the time or inclination to go hassle with the bank each time but do prefer not to get ripped off, make the payment as described: on the dot and at the same time as the regularly scheduled monthly payment. The amortization schedule that the bank should have given you shows how much the principal amount is after the monthly  payment is made on each due date.  Assuming that you have  not been taking advantage of the grace periods and so the schedule is correct, make an additional payment not of a round sum but an exact amount (down to the last penny) that will jump you from principal owing after today's regular payment to principal owing after the regular payment N months from today. Here of course you choose N based on how much extra money you were planning on paying towards your mortgage.  By making the extra payment, you will effectively have cut the length of  the mortgage by n months and the same amortization schedule will apply over the shorter period.  Since very little of the principal is repaid in the early life of the mortgage, an additional principal-only payment can reduce the length of the mortgage by years. Paying a specific amount that matches the amortization schedule also helps if you ever need to hassle with the bank. It is their print-out you are arguing from, and not trying to explain to a clueless bank officer how the bank did not compute interest  correctly after you paid $1500.00 extra at beginning of last month." Let's assume that the bonds have a par value of $1,000.  If conversion happens, then one bond would be converted into 500 shares.  The price in the market is unimportant.  Regardless of the share price in the market, the income per share would be increased by the absence of $70 in interest expense.  It would be decreased by the lost tax deduction.  It would be further diluted by the increase in 500 shares.  Likewise, the debt would be extinguished and the equity section increased.  Whether it increased or decreased on a per share basis would depend upon the average amount paid in per share in the currently existing structure, adjusted for changes in retained earnings since the initial offering and for any treasury shares. There would be a loss in value, generally, if it is trading far from $2.00 because it would be valued based on the market price.  Had the bond not converted, it would trade in the market as a pure bond if the stock price is far below the strike price and as an ordinary pure bond plus a premium if near enough to the strike price in a manner that depends upon the time remaining under the conversion privilege.   I cannot think of a general case where someone would want to convert below strike and indeed, barring a very strange tax, inheritance or legal situation (such as a weird divorce), I cannot think of a case where it would make sense.  It often does not make sense to convert far from maturity either as the option premium only vanishes well above $2.  The primary case for conversion would be where the after-tax dividend is greater than the after-tax interest payment. After reading OP Mark's question and the various answers carefully and also looking over some old pay stubs of mine, I am beginning to wonder if he is mis-reading his pay stub or slip of paper attached to the reimbursement check for the item(s) he purchases.  Pay stubs (whether paper documents attached to checks or things received in one's company mailbox or available for downloading from a company web site while the money is deposited electronically into the employee's checking account) vary from company to company, but a reasonably well-designed stub would likely have categories such as Taxable gross income for the pay period: This is the amount from which payroll taxes (Federal and State income tax, Social Security and Medicare tax) are deducted as well as other post-tax deductions such as money going to purchase of US Savings Bonds, contributions to United Way via payroll  deduction, contribution to Roth 401k etc. Employer-paid group life  insurance premiums are taxable income too for any portion of the policy  that exceeds $50K. In some cases, these appear as a lump sum on the last pay stub for the year. Nontaxable gross income for the pay period: This would be sum total of the amounts contributed to nonRoth 401k plans, employee's share of group health-care insurance premiums for employee  and/or employee's family, money deposited into FSA accounts, etc. Net pay: This is the amount of the attached check or money sent via ACH to the employee's bank account. Year-to-date amounts: These just tell the employee what has been earned/paid/withheld to date in the various categories. Now, OP Mark said My company does not tax the reimbursement but they do add it to my running gross earnings total for the year. So, the question is whether the amount of the reimbursement is included in the Year-to-date amount of Taxable Income. If YTD Taxable Income does not include the reimbursement amount,  then the the OP's question and the answers and comments are moot; unless the company has really-messed-up (Pat. Pending) payroll software that does weird things, the amount  on the W2 form will be whatever is shown as YTD Taxable Income  on the last pay stub of the year, and, as @DJClayworth noted cogently, it is what will appear on the W2 form that really matters. In summary, it is good that OP Mark is taking the time to investigate the matter of the reimbursements appearing in Total Gross Income, but if the amounts are not appearing in the YTD Taxable Income, his Payroll Office may just reassure him that they have good software and that what the YTD Taxable Income says on the last pay stub is what will be appearing on his W2 form.  I am fairly confident that this is what will be the resolution of the matter because if the amount of the reimbursement was included in Taxable Income during that pay period and no tax was withheld, then the employer has a problem with  Social Security and Medicare tax underwithholding, and nonpayment of this tax plus the employer's share to the US Treasury in timely fashion. The IRS takes an extremely dim view of such shenanigans and most employers are unlikely to take the risk. My understanding is that the only tax implication is that any interest income earned on foreign accounts is still taxable in the US if held by a US citizen. If the total across foreign accounts totals more than $10,000 you'll have to report those accounts to the Treasury via FinCEN Form 114, this doesn't create any additional tax obligations, it's just a regulatory measure to stop people from hiding money overseas and not paying tax on those earnings. If the US account is only in your husband's name, and the Australian account is only in your name, there may not be any reporting requirement to the Treasury. Money transferred between spouses is not subjected to gift-tax. You setup a self-directed solo 401k by paying a one time fee for a company to setup a trust, name you the sole trustee, and file it with the IRS. None of these companies offer TPA because it opens them up to profit leaching liability. After you have your trust setup, you can open a brokerage account or several with any of the big names you want (Vanguard, Fidelity, Ameritrade, etc), or just use the money to flip houses, do P2P lending, whatever, the world is your investment oyster. If the company has recurring fees you need to ask what is going on because if they aren't offering TPA services, then what the heck could they be charging you for? I did see one company, I think it was IRA Financial Group, that had the option of having a CPA do TPA for you for a recurring fee, but I would pass on that. The IRS administration requirements are typically just the 5500-EZ that you have to file as a hard copy by July 31 if your investments are worth more than $250k, on December 31. Yes, you have to get the actual form from the IRS, write on it with a pen and mail it to them every year, barbaric. You can either have your accountant do it or do it yourself. If you're below $250k just google solo 401k rule change two or three times a year and don't try to launder money. If anything, the rules will loosen with time, I don't imagine the Republican Congress cracking down on small business owners any time soon. "As far as I can tell there are no ""out-of-the-box"" solutions for this.  Nor will Moneydance or GnuCash give you the full solution you are looking for.  I imaging people don't write a well-known, open-source, tool that will do this for fear of the negative uses it could have, and the resulting liability.  You can roll-you-own using the following obscure tools that approximate a solution: First download the bank's CSV information: http://baruch.ev-en.org/proj/gnucash.html That guy did it with a perl script that you can modify. Then convert the result to OFX for use elsewhere: http://allmybrain.com/2009/02/04/converting-financial-csv-data-to-ofx-or-qif-import-files/" 1040ES uses the smaller number because that's what triggers the penalties.  (That is, you are penalized if what you prepay is less than your total 2013 liability and less than 90% of your 2014 liability.)  However, estimated taxes are just estimates.  If you pay too little, you could face a penalty, but there's no penalty for paying too much -- you'll just get a refund as usual. It seems that your concern stems from the fact that this is the first year you're in this tax situation and so you're unsure if your estimates are accurate.  In your comment to Pete Belford's answer, you also indicated you aren't worried about being unable to pay, but only about accidentally underpaying. In this case, you could just err on the side of caution and pay more than 1040ES says you owe.  (You don't actually file the 1040ES, the calculations are just for your own use.)  For instance, you could prepay based on the higher of your two estimates, if you can afford it; or, if you can't afford that much, hedge the estimate payments up a bit to an amount you can afford that is closer to the higher estimate.  At the end of the year if you paid too much you can get a refund as usual.  After this year, you will presumably have a better sense of your income and your tax liability, and can make more accurate estimates for next year. To start with, I should mention that many tax preparation companies will give you any number of free consultations on tax issues — they will only charge you if you use their services to file a tax form, such as an amended return. I know that H&R Block has international tax specialists who are familiar with the issues facing F-1 students, so they might be the right people to talk about your specific situation. According to TurboTax support, you should prepare a completely new 1040NR, then submit that with a 1040X. GWU’s tax department says you can submit late 8843, so you should probably do that if you need to claim non-resident status for tax purposes.