extra principal payments. But don't write it off completely without a little more analysis. February 9, 2009 Peter M Vaughan @ 5:03 am : Greg, The example given in your link shows that it can save you some money to pay your mortgage off by submitting payments twice a month, not that using a HELOC results in a faster payoff. Because interest compounds daily, it is true that making payments twice a month instead of once a month will save a small amount of interest. However, comparing using a HELOC which is paid twice a month to a mortgage payment made monthly is not a valid way to compare the two methods to determine which most effectively pays off ones home. There is no way to temporarily borrow money at a higher interest rate to pay off money at a lower interest rate and come out ahead in a valid comparison of the two systems. However, I wish you the best of luck in selling your computer program. Peter, The comparisons in my page make one mortgage payment each month. The comparisons are made against two different methods to get the extra principal for the payment. One method uses a HELOC as the source; one method uses what is left over at the end of month. There is not one example that makes multiple mortgage payments - the HELOC methods pay down the HELOC balance twice a month but that is not the same as a mortgage payment and is