Well, what I described was fixed-rate mortgage and adjustable-rate mortage. The interest rate is what changes with an ARM.this is true for the most part. but even if the rate stays fixed, of your property taxes or insurance increase, then your mortgage payment can increase that way. for instance, we had a property tax increase this year, and I'm looking at about $20 a month more in payment.
I've had my monthly mortgage change because of changes in property assessment. So in my case, the value went up, so my property tax went up. I had a fixed-rate mortgage. This can happen but your interest rate on the principal stays the same whether your property tax goes up or down.