Is an interest-only mortgage a bad idea?
Really the question you need to ask yourself is how much Risk you want to take in order to save a little on interest for 5 years. Rates are pretty close to a historic low, and if you have good credit you should shop around a bit to get a good ideal of what a 15 or 30 year fixed loan would go for. For people that are SURE they will be selling a property in a few years, a 5-yeah balloon, or ARM might not be a bad thing.  OTOH, if their plans change, or if you plan to stay in the property for longer (e.g. 10-15 years) then they have the potential to turn into a HUGE trap, and could have the effect of forcing you to sell your house.   The most likely people to fall into such a trap are those who are trying to buy more house than they can really afford and max out what they can pay using a lower rate and then later cannot afford the payments if anything happens that makes the rate go up.  Over the last three years we've seen a large number of foreclosures and short-sales taking place are because of people who fell into just this kind of trap..  I strongly advise you learn from their mistakes and do NOT follow in their footsetps  You need to consider what could happen in 5 years time.   Or if the economy takes off and/or the Fed is not careful with interest rates and money supply, we could see high inflation and high interest rates to go along with it.   The odds of rates being any lower in 5 years time is probably pretty low.  The odds of it being higher depends on who's crystal ball you look at.  I think most people would say that rates are likely to increase (and the disagreement is over just how much and how soon).  If you are forced to refinance in 5 years time, and the rates are higher, will you be able to make the payments, or will you potentially be forced out of the house? Perhaps into something much smaller.  What happens if the rates at that time are 9% and even an ARM is only 6%? Could you make the payments or would you be forced to sell?   Potentially you could end up paying out more in interest than if you had just gotten a simple fixed loan. Myself, I'd not take the risk.  For much of the last 40 years people would have sold off their children or body parts to get rates like we have today on a standard fixed loan.  I'd go for a standard fixed loan between 15 and 30 years duration.  If you want to pay extra principle to get it paid off earlier in order to feel more secure or just get out from under the debt, then do so (personally, I wouldn't bother, not at today's rates) Generally, interest-only mortgages are a bad idea, because a lot of people get them so that they can buy more house than they could otherwise afford (lower payment = affordable, in their minds).  If the house continues to go up in value, they probably get away with it, because when the balance becomes due, they can refinance.  However, the last few years has shown how risky that strategy can be, and this kind of things is what cost a lot of people their houses. In your case, if the house is something you could afford on a regular 15 or 30-year mortgage, and you really are as disciplined as you say you are, you might get away with it.  But you have to take into account the risk, and consider what happens if there is a job loss or similar difficulty in the future. Another thing to consider is the term of the mortgage.  How many years will you get this lower interest rate?  Interest rates are at historic lows right now, and pretty much everyone thinks they're going up soon.  You might be better off locking in a higher rate for 15 years. If you took a fixed loan, but paid it off at the accelerated rate, you would ultimately pay less total dollars in interest. So compare the actual amount paid in interest over the course of the loan rather than the interest rate itself.  That should be your answer. Also, plan on failing in your plan to pay it off and see how that will affect you. Normally interest only mortgages are taken incase one planning to sell off the property after a few years and purchase of the property is for investment. In such a case instead of burdening oneself with a huge EMI, one opts for an interest only mortgage, and towards the end of the term, sell off the house at profit and repay back the entire principal.  I am not to sure if interest only mortgages are encouraged for properties you plan to live in. Although I do not know about the ING scheme, normally there is no prepayment option on interest only mortgages, its Bank way of earning a fixed income for the contracted period and thats the reason why the interest rates are lower than a regular mortgage. If you do the math, you may be paying more in total interest than on a regular mortgage. It's an interesting question, and one that has a few tentacles. A few thoughts come to mind: There's nothing wrong per se with these arrangements. I think it's a matter of doing what feels comfortable. Hopefully someone on here will have a personal experience to share. It seems you understand the risks, it seems like a fine enough idea.  Hopefully it works out for you. However, you may want to talk to a few local banks about getting a short term home equity loan.  I know someone who was able to do this getting a very low rate for 7 years.  At the time of the loan, the prevailing rate for a 15 year was 3.25, but they were able to get the HEL at 2.6 fixed.  There was no closing costs. The best part about it was the payment was not that much more.  While going from ~1200 to ~1800 is a 50% increase it was not that much in dollars in relationship to his household income.   Note that I did not say Home Equity Line of Credit, which are vairable rates and amount borrowed.
take a look at this graph here: http://mortgagevista.com/#m=1&a=40000&b=4&c=30y&B&oa&ob&oc&od It shows how much it costs to borrow $40k for 30 years. You did not post your mortgage rate or loan term, so I used 4% over 30 years (you can easily update this with your actual details). While this does not show the costs of your total mortgage, it does help you get an idea of just how much the 40k$ in question is costing you in interest. If you hover over the month one year from now you will see that you will have paid around $1587 in interest over the course of the year. If you were to put the full 40k$ toward your mortgage right now, you would avoid having to pay this interest over the next year.  The next question I think you would have to ask yourself is if there is anything else you could do with that money that is worth more than the $1587 to you.  Is it worth $1587 to keep those funds liquid/available in case you need to use them for something else? Could you find other investments you feel comfortable with that could earn you more than $1587?  Is it worth the hassle/risk of investing the funds somewhere else with a better return? If you can't come up with anything better to do with the money then yes, you should probably use the funds (or at least part of them) towards the mortgage. "Note: I am making a USA-assumption here; keep in mind this answer doesn't necessarily apply to all countries (or even states in the USA).  You asked two questions: I'm looking to buy a property. I do not want to take a risk on this   property. Its sole purpose is to provide me with a place to live. How   would I go about hedging against increasing interest rates, to counter   the increasing mortgage costs? To counter increasing interest rates, obtaining a fixed interest rate on a mortgage is the answer, if that's available.  As far as costs for a mortgage, that depends, as mortgages are tied to the value of the property/home.  If you want a place to live, a piece of property, and want to hedge against possible rising interest rates, a fixed mortgage would work for these goals. Ideally I'd like to not lose money on my property, seeing as I will be   borrowing 95% of the property's value. So, I'd like to hedge against   interest rates and falling property prices in order to have a risk   neutral position on my property. Now we have a different issue.  For instance, if someone had opened a fixed mortgage on a home for $500,000, and the housing value plummeted 50% (or more), the person may still have a fixed interest rate protecting the person from higher rates, but that doesn't protect the property value.  In addition to that, if the person needed to move for a job, that person would face a difficult choice: move and sell at a loss, or move and rent and face some complications. Renting is generally a good idea for people who (1) have not determined if they'll be in an area for more than 5-10 years, (2) want the flexibility to move if their living costs rises (which may be an issue if they lose wages), (3) don't want to pay property taxes (varies by state), homeowner's insurance, or maintenance costs, (4) enjoy regular negotiation (something which renters can do before re-signing a lease or looking for a new place to live).  Again, other conditions can apply to people who favor renting, such as someone might enjoy living in one room out of a house rather than a full apartment or a person who likes a ""change of scenes"" and moves from one apartment to another for a fresh perspective, but these are smaller exceptions. But with renting, you have nothing to re-sell and no financial asset so far as a property is concerned (thus why some real estate agents refer to it as ""throwing away money"" which isn't necessarily true, but one should be aware that the money they invest in renting doesn't go into an asset that can be re-sold)." "From what I've heard in the past, debt can be differentiated between secured debt and unsecured debt.   Secured debt is a debt for which something stands good such as a mortgage on your house.  You have a debt, but that debt is covered by the value of an asset and if you needed to free yourself of the debt, then you could by selling that asset.   This is what is known as ""good"" debt.   Unsecured debt is debt that is incurred where the only thing that is available to pay it back is your income.  An example of this is credit card debt where you purchase something that couldn't be sold again to pay off the debt.   This is know as ""bad"" debt. You have to be careful about thinking that house debt is always ""good"" debt because the house stands good for it though.  The problem with that is that the house could go down in value and then suddenly your ""good"" debt is ""bad"" debt (or no longer secured).  Cars are very risky this way because they go down in value.  It is really easy to get a car loan where before long you are upside down.    This is the problem with the term ""good"" debt. The label makes it sound like it is a good idea to have that debt, and the risk associated with having the debt is trivialized and allows yourself to feel good about your financial plan.  Perhaps this is why so many houses are in foreclosure right now, people believed the ""good"" debt myth and thought that it was ok to borrow MORE than the home was worth to get into a house.  Thus they turned a secured debt into an unsecured debt and put their residence at risk by levels of debt they couldn't afford. Other advice I've heard and tend to agree with, is that you should only borrow for a house, an education and maybe a car (danger on that last one), being careful to buy a modest house, car etc that is well within your means to repay.   So if you do have to borrow for a car, go for basic transportation instead of the $40,000 BMW.  Keep you house payment less than 1/4th of your take home pay. Pay off the school loans as quickly as possible. Regardless of the label, ""good"" ""bad"" ""unsecured"" ""secured"", I think that less debt is better than more debt.   There is definitely such a thing as too much ""good"" debt!" You should have drafted a contract of purchase that stipulated out equity stake in the home based of his down payment and yours, along with future monthly payments.  But morally, if the house sells, yielding 100,000 profit (after fees/taxes/etc), you should get ( To Calculate Your Cut: (20,000 + Your Total Mortgage Payments Applied to Principle) / (1,900 + His Total Mortgage Payments Applied to Principle Only) * Profit on Sale of House After All Fees = Your Cut His would be: (1,900 + His Total Mortgage Payments Applied to Principle Only) / (20,000 + Your Total Mortgage Payments Applied to Principle) * Profit on Sale of House After All Fees = His Cut You'd then take mortgage payment totals for each; and calculate the payments made towards interest; and claim the correct amount each of you paid on payments for the mortgage interest deduction when you file your taxes. Although, depending on how the loan is written, the banks may issue 1099s which dont reflect actual payments made... Talk to an accountant. Something very similar to this was extremely popular in the UK in the late 1980s.  The practice has completely vanished since the early 2000s.  Reading up on the UK endowment mortgage scandals will probably give you an excellent insight into whether you should attempt your plan. Endowment mortgages were provided by banks and at their peak were probably the most popular mortgage form.  The basic idea was that you only pay the interest on your mortgage and invest a small amount each month into a low fee endowment policy.  Many endowment policies were simply index tracking, and the idea being that by the end of your mortgage you would have built up a portfolio sufficient to pay off your mortgage, and may well have extra left over. In the late 1990s the combination of falling housing market and poor stock performance meant that many people were left with both the endowment less than their mortgage and their house in negative equity. Up to some degree, a higher or lower interest rate means a bit less or a bit more money in your pocket. If the interest rate gets too high, you may be in trouble. So you first look at the situation and ask yourself: At what interest rate would I be in trouble?  If this is a $20,000 student loan, then even a very high rate wouldn't be trouble. It would be unfortunate and unpleasant, but not fatal. For a $800,000 mortgage, that's different. Each percent more is $8,000 a year. Going from 3% to 10% would change the interest from $24,000 to $80,000 a year, which would be fatal for many people.  In a situation where you can afford increasing variable payments without problems you can go for it. If your variable rate would vary over time between 4% and 6% you would still be even. In that situation, go for variable (taking into account where you think interest rates will go in the future). For a mortgage, the security would likely be more important. (On the other hand, if your dad is a multi-millionaire who would help you out, then that big rate increase wouldn't be fatal, and you could go for a variable rate mortgage).  In some countries, you can cancel any loan contract when the interest rate is raised. So raising a variable mortgage interest rate would allow you to look elsewhere without early repayment penalties. Check out if that is the case for you. "It's viable for you,  but the ""investor"" is either stupid or willing and able to write off the investment as a gift for a friend in need, knowing it will probably end the friendship.  The banks make their money off of indebtedness, with the highest returns being on the highest risk loans . If the bank isn't willing to give you that debt on your own,  it's because they already know it's a bad debt. In this case,  trust the banks. If you can't come up with the downpayment on your own, you won't be able to meet your other commitments on this contract." In all likelihood, the best thing you can do, if these really are your only two options (ie no other debt at all), paying-down your mortgage will shorten the term of the mortgage, and mean you spend less on your house in the long run. Investing is should be a long-term activity - so yes, the likelihood is that, given a modest investment, it will gain at historical averages over the life of the investment vehicle. However, that is not a guarantee, and is an inherent risk. Whereas paying-down a mortgage lowers your financial obligations and risk, investing increases your risk. I want to know how you got a 2.1% interest rate on a mortgage, though - the lowest I've seen anywhere is 3.25%.