Is interest on a personal loan tax deductible?
When you pay interest on a loan used to fund a legitimate investment or business activity, that interest becomes an expense that you can deduct against related income. For example, if you borrowed $10k to buy stocks, you could deduct the interest on that $10k loan from investment gains.  In your case, you are borrowing money to invest in the stock of your company.  You would be able to deduct the interest expense against investment gain (like selling stock or receiving dividends), but not from any income from the business. (See this link for more information.) You do not have to pay taxes on the interest paid to your father; that is an expense, not income.  However, your father has to pay taxes on that interest, because that is income for him. Can you deduct interest paid to your father on your personal income taxes? Interest paid on passive investments can be deducted from the amount earned by that investment as an investment expense as long as the amount earned is greater than the total paid for the interest expense. Also beware if the amount of interest paid is greater than the yearly gift tax exclusion, as the IRS might interpret this as a creative way of giving gifts to your father without paying gift tax. Do you pay taxes on the interest you pay?  No, because is an expense, not income, you would not count interest paid to him as taxable income. Does your father owe taxes on the interest he collects from you? Yes, that is income to him. And the last question you didn't ask, but I expect it is implied: Do you owe taxes on the quarterly profits? Yes, that is income to you.   The Forbes article How To Arrange A Loan Between Family Members is a bit dated, but still a good source of information. You really should write a formal note (signed by both you and your father) indicating the amount borrowed, the interest rate you are paying on that amount, and when the loan will be repaid. If your father has set the interest rate too low, this could also be considered a gift to you, though we would really be talking about large amounts of money to hit the gift tax limit on interest alone. "Assuming USA: It is possible to make the interest deductible if you go to the trouble of structuring, and filing, the loan as an actual mortgage on a primary residence. Websearching ""intra-family loan"" will find several firms which specialize in this. It costs about $700 for all the paperwork and filing fees as of last time I checked, so unless you're going to pay at least three times that in interest over the life of the loan it probably isn't worth considering. (For an additional fee they'll take care of the payment processing,  if you'd really rather be hands-off about it.) I have no idea whether the paperwork fees and processing fees can be deducted from the interest as a cost of producing that income. In theory that ought to be true, but I Am Not A Lawyer. Or accountant. Note: one of the interesting factors here is that the IRS sets a minimum interest rate on intra-family loans. It's pretty low (around 0.3%), so in most cases you can say you gifted the difference if you'd prefer to charge less... but that does set a floor on what the IRS will expect the lender to declare, and pay taxes on. There's a lot more that can be said about this, but since I am NOT an expert I'll refer you to those who are. I have no affiliation with any of this except as a customer, once; it seemed pretty painless but I can't claim to know whether they were really handling everything exactly correctly. The website seemed to do a pretty good job of explaining what choices had to be made and their effects, as well as discussing how these can be used to avoid excess gift taxes by spreading the gift over a number of years."
"First off, the ""mortgage interest is tax deductible"" argument is a red herring.  What ""tax deductible"" sounds like it means is ""if I pay $100 on X, I can pay $100 less on my taxes"".  If that were true, you're still not saving any money overall, so it doesn't help you any in the immediate term, and it's actually a bad idea long-term because that mortgage interest compounds, but you don't pay compound interest on taxes. But that's not what it actually means.  What it actually means is that you can deduct some percentage of that $100, (usually not all of it,) from your gross income, (not from the final amount of tax you pay,) which reduces your top-line ""income subject to taxation.""  Unless you're just barely over the line of a tax bracket, spending money on something ""tax deductible"" is rarely a net gain. Having gotten that out of the way, pay down the mortgage first.  It's a very simple matter of numbers: Anything you pay on a long-term debt is money you would have paid anyway, but it eliminates interest on that payment (and all compoundings thereof) from the equation for the entire duration of the loan.  So--ignoring for the moment the possibility of extreme situations like default and bank failure--you can consider it to be essentially a guaranteed, risk-free investment that will pay you dividends equal to the rate of interest on the loan, for the entire duration of the loan. The mortgage is 3.9%, presumably for 30 years.  The car loan is 1.9% for a lot less than that.  Not sure how long; let's just pull a number out of a hat and say ""5 years."" If you were given the option to invest at a guaranteed 3.9% for 30 years, or a guaranteed 1.9% for 5 years, which would you choose?  It's a no-brainer when you look at it that way." The rental income is indeed taxable income, but you reduce the taxable portion of it by deducting expenses (including mortgage interest, maintenance, insurance, HOA, real estate tax, and of course depreciation). Due to the depreciation, you may end up breaking even, or having very little taxable income. Note that when you sell the property, your basis is reduced by the depreciation you were allowed to deduct (even if you haven't deducted it for whatever reason), and also the personal residence exclusion might no longer be applicable - i.e.: you'll have to pay capital gains tax. You will not be able to deduct a loss though if you sell now, so it may be better to depreciate it as a rental, rather then sell at a loss that won't affect your taxes. Also, consider the fact that the basis for the depreciation is not the basis you currently have in the property (because you're under water). You have to remember that when calculating the taxes. This is not a tax advice, and you should seek a professional help. "A loan is not a taxable income. Neither is a gift. Loans are repaid with interest. The interest is taxable income to the lender, and may or may not be deductible to the borrower, depending on how the loan proceeds were used. Gifts are taxable to the donor (the person giving the gift) under the gift tax, they're not a taxable income to the recipient. Some gifts are exempt or excluded from gift tax (there's the annual exemption limit, lifetime exclusion which is correlated to the estate tax, various specific purpose gifts or transfers between spouses are exempt in general).  If you trade for something of equal value, is that considered income? Yes. Sale proceeds are taxable income, however your basis in the item sold is deductible from it. If you borrow a small amount of money for a short time, is that considered income? See above. Loan proceeds are not income. does the friend have to pay taxes when they get back their $10? No, repayment of the loan is not taxable income. Interest on it is. Do you have to pay taxes if you are paid back in a different format than originally paid? Form of payment doesn't matter. Barter trade doesn't affect the tax liability. The friend sold you lunches and you paid for them. The friend can deduct the cost of the lunches from the proceeds. What's left - is taxable income. Everything is translated to the functional currency at the fair market value at the time of the trade. you are required to pay taxes on the gross amount Very rarely taxes apply to gross income. Definitely not the US Federal Income taxes for individuals. An example of an exception would be the California LLC taxes. The State of California taxes LLCs under its jurisdiction on gross proceeds, regardless of the actual net income. This is very uncommon. However, the IRC (the US Federal Tax Code) is basically ""everything is taxable except what's not"", and the cost of generating income is one of the ""what's not"". That is why you can deduct the basis of the asset from your gross proceeds when you sell stuff and only pay taxes on the net difference." Staying with your numbers - a 7% long term return will have a tax of 15% (today's long term cap gain tax) resulting in a post tax of 5.95%. On the other hand, even if the student loan interest remains deductible, it's subject to phaseout and a really successful grad will quickly lose the deduction.  There's a similar debate regarding mortgage debt. When I've commented on my 3.5% mortgage costing 2.5% post tax, there's no consensus agreeing that this loan should remain as long as possible in favor of investing in the market for its long term growth. And in this case the advantage is a full 3.45%/yr. While I've made my decision, Ben's points remain, the market return isn't guaranteed, while that monthly loan payment is fixed and due each month.  In the big picture, I'd prioritize to make deposits to the 401(k) up to the match, if offered, pay down any higher interest debt such as credit cards, build an emergency account, and then make extra payments to the student loan.  Keep in mind, also - if buying a house is an important goal, the savings toward the downpayment might take priority. Student Loans and Your First Mortgage is an article I wrote which describes the interaction between that loan debt and your mortgage borrowing ability. It's worth understanding the process as paying off the S/L too soon can impact that home purchase. If you end up keeping the student loan, it will be a tax deduction.  Probably not much but at least it's something. The reason it's broken out is very specific: this is showing you how much interest accrued during the month.  It is the only place that's shown, typically. Each month's (minimum) payment is the sum of [the interest accrued during that month] and [some principal], say M=I+P, and B is your total loan balance.  That I is fixed at the amount of interest that accrued that month - you always must pay off the accrued interest.  It changes each month as some of the principal is reduced; if you have a 3% daily interest rate, you owe (0.03*B*31) approximately (plus a bit as the interest on the interest accrues) each month (or *30 or *28).  Since B is going down constantly as principal is paid off, I is also going down. The P is most commonly calculated based on an amortization table, such that you have a fixed payment amount each month and pay the loan off after a certain period of time.  That's why P changes each month - because it's easier for people to have a constant monthly payment M, than to have a fixed P and variable I for a variable M. As such, it's important to show you the I amount, both so you can verify that the loan is being correctly charged/paid, and for your tax purposes. "For this type of loan, to be considered ""arm's length,"" the rate needs to be fair (you got that covered), the loan must be secured against the house, via a lien, else it may be considered a non-deductible personal loan, and last, you need the 1099.  You might get away with the first 2, as he's claiming the interest, but the lien is key." I would not expect any problems. Your interest will have tax deducted at 20% which I don't think you would be entitled to reclaim because you don't get a personal allowance if you aren't resident in the UK, and unless you have a huge amount of UK earnings you would not be legally liable to any higher rates of tax so there would be no issues there. If you were liable to more tax you would be obliged to inform the Inland Revenue.