The answer is yes even if you have a fixed rate mortgage. One reason is adjustments to your escrow account.

Adjustments to your escrow account are changes in your taxes and insurance. If the cost of your taxes or insurance changes, so will your monthly payment. This only applies if you do include your taxes and insurance in your monthly payment.

If you have an adjustable rate mortgage currently, your loan may fluctuate based on what type of loan product you have. There are many different times when an adjustable rate mortgage may change. Some are annually, semi-annually, every three months or even monthly. You need to check with your current mortgage loan company to find out what terms you agreed to at closing. You may be able to refinance to a fixed rate mortgage to avoid these changes in rates.

If your loan is sold from one lender to another they will always have to abide by the original terms of your mortgage contract. If you had an ARM they cannot change your adjustment period, or the amount of your maximum interest rate adjustment. The same is true on a fixed rate mortgage. No matter how many times your loan is sold you will retain the same interest rate, repayment term, etc. Of course, you are still subject to changes in you payment due to tax and insurance fluctuations if you escrow.

If you have a mortgage with an "Interest Only" feature that requires you to make payments on only the interest accrued for the previous month, such as a "Pay Option ARM" mortgage, your interest-only payment can change if you pay down your principal during the prior month.

Some fixed rate mortgages come with an interest only period where only the interest portion of the payment is required for a pre-set amount of time. After the interest only period is over the payment must then increase in order to pay off the loan by the time it is due. Even though the payment can increase the interest rate is in fact fixed for the entire term.