What Is a Mortgage Rate Lock and Should I Use One?

A rate lock guarantees your mortgage interest rate and points for a set period, usually 30 to 60 days, protecting you if rates rise before your closing. Once you lock, your lender is committed to that rate for the length of the lock, provided you close within it.

The lock turns an unpredictable rate into a known number, which matters because mortgage rates can move daily. Between your application and closing, that protection can be worth thousands of dollars.

A rate lock is a promise from the lender backed by the terms of your loan commitment: it fixes both the rate and the points, so the payment you are shown at lock time is the payment you can plan around.

Rate locks come in set lengths, and longer locks generally cost more or carry a higher rate. A typical lock runs 30, 45, or 60 days, chosen to match your expected closing date. If your closing is delayed beyond the lock period, you may need to pay a fee to extend it, or accept the current market rate.

That is why the timing of your lock matters: lock too early and you pay for days you do not need; lock too late and you risk rates moving against you while you wait.

Ask your lender for the extension terms before you lock: how much a one-week or one-month extension costs, and whether there is any grace period. Knowing the fallback before a delay happens keeps a paperwork snag from becoming a rate problem.

The right time to lock is once you have a ratified contract and a realistic closing date, not before. Before you are under contract, the rate is a quote that can change, and locking too early can expire before your closing. Once the contract is signed and the date is set, locking protects you for the window you actually need.

If rates are rising, locking sooner makes sense. If rates are stable or falling, you may choose to float and lock closer to closing. Your lender advises on the timing based on the current market.

Every lender has its own policy on when a lock can begin and when it must be in place, so confirm the earliest lock date when you apply and ask for the lender's read on the rate trend so your timing decision is an informed one.

Floating means you leave the rate uncommitted, hoping it falls before you lock, while locking means you accept today's rate as your guaranteed number. Floating can save money if rates drop, but it exposes you to rising rates. Locking trades that upside for certainty.

Most buyers choose certainty, especially in a market where rates are volatile. Ask your lender for their perspective on the market and whether they offer a float-down option, which lets you take a lower rate if it drops after you lock.

A float-down provision is the best of both worlds when it is offered at a reasonable cost: you keep the guaranteed ceiling of the lock and still capture a lower rate if the market cooperates, and asking for it is free.