Comment by AnimalMuppet

But it doesn't, does it?

If I have $300K on my mortgage and a monthly payment of $2000, and I pay an extra $100K, that 100K reduces the principal of the mortgage by $100K, and so the mortgage will run for several years less than it would have. But my monthly payment is still $2000 for the years I have left on it.

There are other ways to structure it - you can pay ahead, paying next month's payment this month so that you don't have to pay anything next month if you don't want to. Can you pay $100K so that you don't have to pay the next 50 months' payments? I don't know, but probably. You have to be clear with them what you are trying to do, though.