Main Points When Locking In

Lock in as many of the costs you can, the rate as well as points.

Whatever lock you choose, get the guarantee in writing. Oral agreements are difficult to prove should it come to that.

Unless your contract says otherwise, a rate lock could also prevent you from taking advantage of lower rates, should rates decrease.

Shop around for both the terms of the lock contract and its cost. Some lenders may charge you an up-front, non-refundable fee should you withdraw your application, if your credit is denied, or if for some other reason you don't close the loan. Others might charge the fee at settlement. The fee might be a flat fee, a percentage of the mortgage amount, a fraction of a percentage point or a higher interest rate. Some lenders offer the service at no cost.

If you see a rate you want, set the lock ''on application'' rather than ''on approval.'' On approval means you won't have a stab at rates until the loan application is approved. That could be weeks away and rates could change unfavorably just as they have in recent days.

The lock-in period should be long enough to allow for settlement, contingencies imposed by the lender or purchase contract and other factors that could delay the process.

Before deciding on the length of the lock-in, find out the average time for processing loans and ask your lender to estimate (in writing, if possible) the time needed to process your loan. Consider all factors that could delay your settlement, including the time it will take you to provide requested materials about your financial condition, unanticipated construction delays on a new house and the like.

Consider current market conditions as well. Right now mortgage lenders offering competitive rates are flooded with mortgage applications.