What Is a Rate Lock? Extensions & Float-Downs
October 20, 2026
A mortgage rate lock is a lender's commitment to hold a specific interest rate and price (points or lender credit) for a set period while your loan is processed, as long as your application doesn't change. Without a lock, your rate and costs can move with the market every day until closing. Your Loan Estimate shows whether your rate is locked and when the lock expires, right at the top of page 1.
How a rate lock works. When you lock, the lender sets your interest rate and the related points or lender credit for a lock period, often 30, 45 or 60 days. Longer locks are available but can cost more. A lock is tied to your loan details. If your loan amount, credit score, property value, occupancy or loan type changes, your pricing can change even while you're locked. Once you lock, the lender must send you a revised Loan Estimate within three business days that shows the locked terms. Get any lock confirmation in writing, with the rate, points or credit, the expiration date and the time zone.
Rate lock extensions and re-locks. If closing is delayed past the expiration date, you'll usually need a lock extension. Lenders often charge for extensions, and who pays may depend on what caused the delay. If a lock expires, the lender may re-price the loan at the current market or the worse of the original and current pricing, depending on its policy. Before you lock, ask: how long is the lock, what does an extension cost, who pays if the lender causes the delay, and what is your re-lock policy?
What is a float-down? A float-down option lets you take a lower rate if market pricing improves after you lock. Lenders may charge for it and usually limit it to one use, set a minimum improvement, and set timing rules. A float-down isn't automatic, so you must ask for it. Whether it's worth it depends on its cost and how long until closing. Compare it with simply floating, which means waiting to lock and taking the risk that rates rise.
A rate lock protects your interest rate and pricing for a set period, as long as your loan details don't change. Confirm the lock in writing, match the lock period to your realistic closing timeline, and ask upfront about extension costs, re-lock rules and float-down options. Check page 1 of your Loan Estimate to see whether you're locked, and look for a revised Loan Estimate after you lock. General education only. LoFi Rate is an independent matching service, not a lender.