Mortgage Rate Lock: Explained in Plain English
Article Summary
A mortgage rate lock is a lender's written commitment to hold a quoted interest rate and its points for a set number of days while the loan moves to closing, as long as the application doesn't materially change.
A mortgage rate lock is a price agreement between you and your lender with three parts: an interest rate, a cost, and a time frame. The rate is the one you'll pay on the loan. The cost is the number of discount points attached to that rate, which can be zero. The time frame is how many days the lender promises to honor both.
Until you lock, your quoted rate floats with the market and can change daily. Once you lock, the lender holds the rate and points even if rates rise before you close, which is the entire point of the agreement. Per the Consumer Financial Protection Bureau, the lock holds as long as you close within the specified time frame and nothing material about your application changes.
That second condition matters. A lock freezes the price for the loan you applied for. If the loan itself changes, the price can too. Lenders can reprice a locked rate when your credit score drops, your loan amount or down payment changes, the appraisal comes in low, your income can't be verified as stated, or you switch loan programs. The lock protects you from the market, not from changes to your own file.
The Basics
- A rate lock freezes your interest rate and points for a set number of days while your loan closes
- Most lenders lock a purchase loan only after you have a signed contract, and your Loan Estimate shows whether you're locked
- Standard locks run 30 to 60 days; longer locks and extensions usually cost more
- A lock protects you from rising rates but doesn't lower your rate if the market falls, unless you have a float down
When Can You Lock a Mortgage Rate?
For a home purchase, most lenders lock only after you have a signed purchase contract. The lock has to attach to a specific property, loan amount, and closing date, and none of those exist until a seller accepts your offer. In my work as a loan officer, the accepted offer is the trigger: the contract arrives, the lock gets requested, and the clock starts.
A few lenders offer lock-and-shop programs that let you freeze a rate while you're still house hunting, typically for a fee or at a somewhat higher rate. They're the exception, and they're worth asking about only if you expect to find a home quickly in a rising-rate market.
Your proof of lock is your Loan Estimate. The top of page 1 states whether your rate is locked and, if so, the date and time the lock expires. The CFPB's advice is to check that box directly rather than assume, because some lenders lock when they issue the Loan Estimate and some don't. If the rate on the form doesn't match the rate you were quoted, our Q&A on why a Loan Estimate can show a different rate explains the usual causes, and locking is the fix for most of them. Our Q&A on how to verify your rate is actually locked covers what to do if the box says no and you thought it said yes.
Refinances work differently. There's no contract to wait for, so you can lock as soon as your application is complete and you're comfortable with the quote.
Lock or Float: Is It a Good Idea to Lock?
Locking is a decision about risk, not a prediction about rates. When you lock, you know your payment. When you float, you're betting that rates will be lower on the day you'd otherwise have locked, and you're carrying the risk that they'll be higher.
For most buyers, the case for locking is simple. You've already committed to a purchase price and a closing date, so the mortgage payment is the last unknown in your budget, and a lock removes it. For example, on a $350,000 30-year fixed loan, a half-point rise in the rate adds roughly $115 to the monthly principal-and-interest payment for the life of the loan, and that kind of move can happen in a few weeks. A standard-length lock typically costs little or nothing and eliminates that exposure.
Floating makes sense in a narrower set of cases. If you could comfortably afford the payment at a meaningfully higher rate, you may decide the upside is worth the risk. If your closing is more than 60 days out and a long lock is expensive, floating for a few weeks and locking later can save the long-lock premium. And some lenders offer a float down option, discussed below, that lets you lock now and still capture a drop later.
What rarely works is trying to time the bottom. Rates respond to inflation data, Federal Reserve communications, and the mortgage-backed securities market, none of which move on a schedule that lines up with your closing. Our Q&A on locking versus the hedging strategies lenders use explains why lenders themselves don't try to time it either.
How Long Should You Lock For?
Lock periods typically come in 15-day steps: 15, 30, 45, 60, and sometimes 90 days or longer. Quoted rates usually assume a 30-day lock. Shorter locks can earn a small credit; longer locks cost more, because the lender is carrying market risk for a longer stretch.
Here is how lock length can affect cost. This table uses sample pricing to show the shape of the trade; actual adjustments vary by lender and by day.
Cost Summary: Mortgage Rate Lock Lengths
| Rate Lock Length | Estimated Cost Impact |
|---|---|
| 15-day | 5 basis point credit |
| 30-day | Standard rate |
| 45-day | 7 basis points |
| 60-day | 13 basis points |
| 90-day | 25 basis points or more, sometimes with an upfront fee |
A basis point is one hundredth of a percentage point, and these adjustments usually show up as a change in points or lender credit rather than in the rate itself.
The rule for choosing: pick the lock that covers your expected closing date with a cushion. If your contract says you close in 30 days, a 30-day lock leaves zero room for a delayed appraisal or a title issue, and extending a lock usually costs more than choosing a longer one up front. A 45-day lock on a 30-day closing is often the cheapest insurance in the transaction. Our guide to the closing disclosure explains the three-day waiting period at the end of the process, which is one more reason to leave room.
For the full ladder of lock lengths, what windows beyond 90 days cost, and how to match a window to a realistic closing timeline, see our guide to how long you can lock in a mortgage rate.
What Happens If Rates Drop After You Lock?
Your rate stays locked. That's the trade you made: protection from increases in exchange for giving up decreases. If rates fall meaningfully after you lock, you have three realistic paths.
The first is a float down option, if your lock includes one. A float down lets you reset to a lower rate, usually once, if the market drops by a set amount before closing. It typically costs something, either an upfront fee or a slightly higher starting rate, and it comes with fine print about how far rates must fall and how close to closing you can use it. Our Q&As on what a float down is and what terms to look for and the fine print when a lender is pushing one go through the details.
The second is asking your lender to renegotiate. Some lenders will relock at current pricing, sometimes for a fee and sometimes only if the drop is large. The Q&A on rate locks versus lock-and-renegotiate policies explains how those policies differ.
The third is closing at your locked rate and refinancing later if the lower rates hold. That costs a second set of closing costs, so it only pays when the gap is wide and you expect to keep the loan for years.
What you can't do is quietly switch to the lower rate on your own. The Q&A on whether you get the lower rate automatically has the direct answer: no, not without one of the paths above.
What Happens If Your Rate Lock Expires?
If closing slips past your lock's expiration date, the locked pricing goes away and you have two choices: extend the lock or relock at current pricing.
Extensions are the common fix. Most lenders sell them in short increments, often a week or two at a time, priced as a fraction of a point per extension. The cost lands on your closing disclosure as a charge or as a slightly worse rate. Who pays depends on why closing slipped: buyers commonly absorb it when their own paperwork caused the delay, and sellers or the lender sometimes cover it when the delay was theirs, though none of that is automatic and it's worth negotiating early.
Relocking means starting over at today's market. Many lenders use worst-case pricing when a lock expires, giving you the higher of your original rate and the current one, so an expired lock rarely turns into a windfall even when rates have fallen.
The cheapest expiration is the one you avoid. Ask your lender in advance what an extension costs and how many days they'll grant, and if your closing date is soft, lock long enough to cover the realistic timeline rather than the hopeful one. For the full extension mechanics, including what increments cost and who typically pays, see our guide to rate lock extensions and what they cost.
Can You Get Out of a Rate Lock?
Yes. A rate lock obligates the lender to honor the rate. It doesn't obligate you to take the loan. You can let the lock expire, ask for a relock, or walk away and apply somewhere else.
The costs are practical. You give up the locked rate, which matters if rates have risen. Any lock fee you paid up front is usually nonrefundable. Switching lenders resets the underwriting clock, and a new lender needs time to reach closing, so a switch late in the process can put your contract's closing date at risk. Your appraisal may not follow you either: the original lender has to agree to release it to the new lender, and many won't, so plan on paying for a second one.
Switching to chase a lower rate elsewhere is worth it only when the difference is large, the new lender can close on your contract timeline, and the seller is willing to wait if they can't.
What a Rate Lock Agreement Should Say
Your lock should be confirmed in writing, and the confirmation should answer five questions without you having to ask:
- The exact interest rate and the number of points attached to it
- The lock period and the date and time it expires
- What the lender will charge to extend, and in what increments
- Whether the lock includes a float down, and on what terms
- What happens to the pricing if the lock expires before closing
If any of those are missing, ask for them in writing before you rely on the lock. The Loan Estimate confirms that you're locked and until when, but as the CFPB notes, it won't tell you what the lock cost or what an extension would cost, so the lock agreement is where those numbers live.
Mortgage Rate Lock: A Real World Example
A first-time buyer gets an offer accepted on a Tuesday with a closing date 35 days out. That afternoon, the signed contract goes to the lender, and the buyer asks to lock. The lender offers a 30-day lock at the quoted rate or a 45-day lock for a small added cost. The buyer takes the 45, reasoning that a 35-day closing leaves no room on a 30-day lock.
Two weeks later, an inflation report surprises the market and mortgage rates jump. The buyer's rate doesn't move; the Loan Estimate still shows it locked, with the expiration date a comfortable ten days past closing.
Then the appraisal comes back late, and closing slides by a week. On a 30-day lock, the buyer would now be paying for an extension or relocking at the higher market rate. On the 45-day lock, nothing happens. Closing lands on day 42, the rate is the one from Tuesday, and the extra cost of the longer lock turns out to have been the cheapest line item in the whole transaction.
Common Questions About Mortgage Rate Locks
Common questions about when a rate is locked, whether locking is a good idea, and what happens when rates move or a lock runs out.
