A rate lock is a written guarantee from your lender that the interest rate, points, and lender credits on your mortgage won't change between the day you lock and the day you close — as long as you close within the lock period. Standard locks commonly run 30, 45, or 60 days, with longer locks available for an added cost.
Locking protects you against the market moving against you while your loan is in underwriting. The trade-off: if the market moves in your favor after you lock, you generally don't get the better terms unless your lender specifically offers a float-down option.
How it works
When you lock, your lender records the exact rate, points, and credits tied to your loan and issues a lock confirmation showing the lock period and expiration date. From that point forward, those numbers are fixed for your loan as long as nothing material about your application changes and you close before the lock expires.
If your closing gets delayed — a common outcome when a seller needs extra time or a document takes longer to process — most lenders can extend the lock, typically for a fee. Extension costs are usually modest compared to the risk of letting the lock expire mid-process.
Some lenders offer a one-time float-down: if the option is in your lock agreement and conditions improve before closing, you can ask to reprice down once. It's not automatic and not universal — confirm in writing whether your specific lock includes it.
When it matters to you
Rate locks matter most the moment your offer is accepted and your loan moves into underwriting — that's typically when borrowers lock, to remove uncertainty for the rest of the transaction.
They matter again any time a closing date slips. Track your lock expiration date closely and tell your loan officer immediately about any timeline change so the lock can be extended before it lapses.
Common mistakes
- Letting a lock expire because a closing delay wasn't communicated to the lender in time.
- Assuming every lender offers a float-down option — ask specifically and get it in writing rather than assuming.
- Locking too early, before you're confident in your closing timeline, and paying extension fees that could have been avoided.
- Not understanding that a lock is tied to the specific loan terms on file — a significant change to your loan amount or program can require a new lock.
FAQs
How long does a rate lock last?
Standard locks commonly run 30, 45, or 60 days. Longer lock periods are available from most lenders for an additional cost, which is useful for new construction or longer closing timelines.
What happens if my rate lock expires before closing?
You'll typically need to extend the lock (often for a fee) or re-lock at current market terms, which could mean a different rate than you originally secured. Talk to your lender the moment you suspect a delay.
Can I get a better rate if the market improves after I lock?
Only if your lock agreement includes a float-down option, and even then usually just once. Confirm whether this feature is included before you lock, since it's not standard on every loan.