how long can a lender lock in a rate 
typically a lender can lock in a rate for 30 45 or 60 days 1the bottom linea loan rate lock is an agreement between a mortgage lender and a borrower to lock in an interest rate up to the loan s closing since interest rates fluctuate a rate lock helps protect the borrower from a rate increase and a higher monthly payment however there is a cost to the borrower either as a fee or as a margin added to the rate by the lender 