An example of my own mortgage. I make my mortgage payment and balance goes to XX,990.00. On the amortization schedule, I'm at payment # 151/360. I make the 90.00 overpayment the following week so now my balance is XX,900.00. On my amortization schedule, I'm now at payment 152/360 just from making the overpayment. So I've cut off another month with a small overpayment and inch ever closer to paying off my mortgage faster than somebody who just pays the minimum payment and will for the next 30 years.