A rate lock is a lender's written commitment to hold your interest rate and the points or credits tied to it for a set period, as long as you close within that time and nothing material in your application changes. The CFPB describes locks as typically available for 30, 45 or 60 days, sometimes longer (CFPB). If your loan amount, credit, income, property value or program changes, the lock can be repriced. If the lock expires before closing, it has to be extended or relocked under the lender's policy. A lock is about price. It isn't a loan approval.
A lock confirmation names the loan it applies to. Typically that includes:
The lock holds the price for that combination of facts. If the facts change, the lock is revised to match the new loan, and the revision can cost more or less. That isn't the lender taking the lock away. It's the file no longer matching what was locked.
The CFPB lists common reasons a locked rate can still change (CFPB):
These are the same kinds of events that can trigger a revised Loan Estimate as a changed circumstance.
Regulation Z builds the lock into your disclosures:
The CFPB also points out what the Loan Estimate won't show: how much you're paying for the lock period you chose, what a shorter or longer lock would cost, or what an extension would cost. You have to ask.
Longer lock periods generally cost more, because the lender is holding the price longer, and shorter ones cost less but leave less room for delays. The right length is the one that covers your actual timeline with a cushion: the contract closing date, how long the appraisal is likely to take, title work, any repairs, and for new construction, the builder's completion date. See new construction for builder timelines and extended locks.
Locks expire on a specific date and time, not when the loan is "basically done." Ask exactly which event, signing or funding, has to happen before the deadline under your lender's policy.
Locking protects you if pricing gets worse, and it gives up the chance to benefit if pricing improves. Floating does the opposite. Neither is always right, and nobody can promise which way the market moves. The facts that matter are your contract date, how close you are to closing, how much a move in price would affect your budget, and your own tolerance for risk. Many buyers lock once they're under contract and the timeline is clear. Read how mortgage rates are set for what moves pricing day to day.
This example is made up and uses no rate or price figures. Dana locks her conventional loan in Fort Worth for 45 days after signing a contract with a 40-day closing. The appraisal comes in low, her loan-to-value goes up, and mortgage insurance is now required. The lock on the old structure doesn't automatically apply to the new one, so the lock desk reprices the loan for the new loan-to-value and sends a revised Loan Estimate. Then the seller asks to push closing back a week, past Dana's lock expiration. Before agreeing, Dana asks me for the written extension cost so she can weigh it in the negotiation.
Those are the CFPB's own suggested questions, and every one deserves a written answer.
Under contract and wondering when to lock? I'll match the lock period to your actual closing timeline, tell you in writing what an extension would cost, and walk you through what could reprice the lock before closing. Schedule a call, or when you're ready, start an application.
Links checked Oct 21, 2026.
About the author: McKade Lively, NMLS 2704474, American Pacific Mortgage Corporation dba True North Home Loans, NMLS 1850.
Equal Housing Opportunity.
Last reviewed: Oct 2026