Home refinancing is when you have an existing mortgage on your home and you apply for a new loan to pay off the first one. Normally refinancing is done to lower the interest rate and the payment on your mortgage. If you can get a lower interest rate than you currently have, you'll be able to save substantially on your monthly payments. Additionally, you should consider refinancing into a 15 year mortgage that has a shorter term. This may leave your payments about the same, but expedite paying your home off faster.
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Before you consider refinancing, be sure to determine if the amount you save in interest offsets the amounts you pay in closing costs for the new loan. Also be sure you know why you are refinancing. Do you want a lower payment or possibly a shorter loan term? Do you want to take out some of the equity you have in the house?