Some rules need to keep in mind: 1. Almost all the lenders are no prepay penalty but with 4-6 months no payoff/refinance restriction. 2. No prepay penalty means you can always pay more principle as original scheduled. However, you need to be alert about the extra amount you pay. If your original mortgage payment is $3000 per month, for example, and you pay $4000, it is OK since all the extra $1000 will go to your principle. But if your loan amount is 400K in the first month and you reduced the loan amount to 200K within 6 months, then you will have trouble because the rate you lock is directly related with the loan amount, the less your loan, the higher your rate in general. Also the lender's commission to brokers are also based on your loan amount. You can not get the same rate/rebate for 400K loan vs. 200K. In this case, lender will ask the broker to pay the penalty, who will send the bill to you since you signed the agreement with brokers. Make sure you don't make lenders feel that you have bad intention by paying extra mortgage. Any extra payoff which might cause any potential risk to impact your rate or broker commission will be considered as bad intention. But after the 6 months, you are free to do whatever you like, refinance or even payoff the loan. Hope it helps to clear your mind. Best luck!