<p>istoomuch -- I get ticked off by your "I've got a secret" attitude. "If I told you the numbers, you wouldn't believe me".... I think the truth really is that you are doing a poor job of explaining yourself. The numbers are pretty easy to figure out. </p>
<p>An amortization schedule is something that shows what the payments are, and the balance between interest and principle, for the term of the loan. The "term" is the contractual term - that is, if you have a 30 year loan, but want to pay it off in 15 years, the amortization will be calculated over the remaining term on your loan - and at least in theory that is going to mean that the 30 year loan is going to charge more interest.</p>
<p>However, I have now worked out this problem on half a dozen different amortization calculators - and they all yield the same result: if you prepay the 30 year loan by making monthly payments of the amount needed to make up the difference between the scheduled payments for 15 & 30 year loans, the end result in terms of principal and interest paid is equivalent. Why the math works out that way, I don't know.</p>
<p>There's a very good calculator with great visuals (charts) to show the effect of prepayments here:
<a href="http://www.partnersfirst.com/MortgLoanCalc.html%5B/url%5D">http://www.partnersfirst.com/MortgLoanCalc.html</a></p>
<p>There is an article that has a reasonably good - and simple - explanation about amortization here:
<a href="http://www.dignitymortgage.com/MortgageIndustry/AmortizationTerm.htm%5B/url%5D">http://www.dignitymortgage.com/MortgageIndustry/AmortizationTerm.htm</a></p>
<p>Prepayments reduce both the overall length of the mortgage (it is paid off sooner) and the interest charged. </p>
<p>Interest is always calculated based on the remaining balance of the loan; so if you currently owe $100K on your mortgage send a check to your mortgage lender today for $10,000.00 -- then with the next payment due the interest will be calculated based on the approximately $90K remaining principal balance. </p>
<p>The actual mathematical formula that does this is here:
<a href="http://www.ynot2day.com/TEMPLATES/PROJECTS/MATHEMATICS/APPLIED/FINANCIAL/LOAN%5B/url%5D">http://www.ynot2day.com/TEMPLATES/PROJECTS/MATHEMATICS/APPLIED/FINANCIAL/LOAN</a></p>
<p>The point of confusion may be with "payments" and "interest". The mortgage lender will NOT reduce the monthly payment because principal owed went down -- if you owed $800 a month and prepay an extra $200 a month -- and then 10 years down the line run short of money, that does not mean that your payment due will be less than $800 (unless you have an adjustable mortgage, where the payment IS recalculated whenever the rate changes).</p>
<p>If you have a 30 year mortgage for $100,000 at 5% interest, and you calculate what amortization would be for a 15 year loan, and then pay the diference each month as an additional prepayment - your out of pocket and overall costs will be very close to what you would get if you had negotiated a 15 year loan -- at the end of 15 years you would have paid about $144,000 total. If instead of prepaying monthly, you save your money in the bank - at the end of 15 years you will owe about $65,000 - if you pay that, your overall costs will end up at about $165,000. So basically, waiting until the end of the 15th year costs +$21,000. </p>
<p>If you have an extra $44,000 that you can invest, there is a good chance that you can do better than +$21,000, and come out ahead. But not so good of a chance if you have to build up that account with monthly contributions to savings. And if you don't make more on your savings, deferring the payments is going to cost you half again as much in interest as if you prepay. </p>
<p>Istoomuch -- the clients you talk about who are caught short when their circumstances change are those who planned poorly - they rendered themselves "house poor" by buying more house than they could afford, with payments that left them no room for other savings. I am certainly not advocating that. But it is just as likely that if they had opted for longer mortgages and lower payments that their situation would be worse: they would have the same financial reversal, would have spent their savings on something else that seemed important at the time --and they would have even less equity in their home. The problem with your logic is simply that you assume that they would have managed their money better if they had held on to more cash... but the reality is that cash in the bank is always a temptation. It is a lot easier to spend money that you have than money that you don't have.</p>