Interest rates on mortgage loans can be unpredictable, and they might fluctuate multiple times during your application and closing process. To avoid uncertainty and preserve your ideal rate, ask your lender about locking it in.
When getting a mortgage loan, your lender will ask if you want to "lock" your interest rate for a set period or "float" it until closing.
Locking your mortgage rate means it won't change, as long as your loan closes before the lock expires. If you don't lock it immediately, your lender may offer a window to do so later.
Once you find the rate you want, lock it in ASAP, since there's no guarantee rates won't rise.
Buying or refinancing? Let's make sure you get the best interest rates!
If rates rise and you haven't locked in:
Mortgage rate locks help shield you from rising interest rates while your loan is being processed. They typically last at least 30 days, giving lenders time to finalize the paperwork.
If your loan isn't ready when the lock expires, you may have to renegotiate or accept a new rate.
Note: If rates drop during your lock-in period, you typically can't take advantage of the lower rate unless your loan has a "float down" clause.
Behind the scenes, lenders price rate locks using something called basis points, where 100 basis points equals 1% of your loan amount. Longer lock periods cost more because the lender is taking on more market risk by guaranteeing your rate further into the future. A 15-day lock is typically the cheapest option, while 45- or 60-day locks carry a slightly higher rate or fee to compensate the lender. If your closing timeline is tight, a shorter lock can save you money, but only if you're confident the loan will close on schedule. According to the Consumer Financial Protection Bureau, your rate lock can still be voided if your application details change, including your loan amount, credit score, or verified income, so it pays to keep your finances stable between application and closing.
New construction loans work a little differently. Because build timelines can stretch for months, some lenders offer extended rate locks of 90, 120, or even 180 days specifically for construction-to-permanent loans. These extended locks almost always come with a higher fee than a standard 30- or 45-day lock, since the lender is exposed to market movement over a much longer window. If you're building rather than buying an existing home, ask your loan officer about extended lock options early, since a standard 30-day lock won't cover a six-month build schedule.
Even with a rate lock, your interest rate may still change if:
Your lock agreement should include:
You can withdraw your application and start over, but consider these risks:
Still, if the rate drop is significant, restarting might save you thousands long-term.
Most borrowers lock their rate once they accept a lender's offer.
If you like the current rate and worry it may rise, lock it in immediately. If you think rates may fall, ask your lender if you can wait or delay the lock.
If you're still unsure whether to lock now or float, a simple gut check can help. Lock your rate if the payment fits comfortably into your budget today, if your closing is coming up soon, or if you'd rather have certainty than chase a better deal. Consider floating a little longer only if you have a longer runway before closing, your finances can absorb a modest rate increase, and there's a clear reason, like a scheduled economic report, to expect rates to move down. Most homebuyers who aren't actively tracking bond markets are better off locking once they're comfortable with the payment, since trying to time the exact bottom of a rate cycle is difficult even for professionals.
Rate locks typically last 30–60 days.
Work with your lender to choose the appropriate length based on how long it will take to close.
If delays occur, you may need to pay for a rate lock extension, or the lender may cover it.
A "float down" lets you take advantage of lower rates during your lock period.
Not all lenders offer float-down options, and there may be:
Ask your lender about their float-down policy before you lock in.
Most rate locks are free, but some lenders charge a small fee, especially for longer lock periods. The cost is typically minor compared to the savings of avoiding a rate increase.
To put that in perspective: on a $400,000 loan, a rate increase of just a quarter of a percentage point can add roughly $50 to $60 to your monthly payment. Over a five-year period, that difference adds up to several thousand dollars, which is why even a modest rate lock fee is usually worth paying if it protects you from that kind of swing.
Related: Benefits of Buying a Home
Can I switch lenders after locking my rate? Yes, but you'll typically forfeit any rate lock fee you already paid and start the process over, including a new credit check and, in some cases, a new appraisal. It's usually only worth it if the new lender's terms are significantly better.
Does locking my rate guarantee my loan will be approved? No. A rate lock only guarantees the interest rate, not loan approval. You'll still need to clear underwriting, which reviews your income, assets, credit, and the property itself.
What happens if my closing date moves and my lock expires? Talk to your lender as soon as you know about the delay. Many lenders will extend the lock for a fee, and some will cover a short extension at no cost if the delay wasn't caused by you.
Is a shorter or longer rate lock better? Shorter locks (15 to 30 days) are usually cheaper but only work if you're confident your closing timeline won't slip. Longer locks (45 to 60 days) cost a bit more but give you a cushion if your transaction takes longer than expected.
Looking for the best rates for your mortgage loan? Get in touch with the loan brothers at Mares Mortgage! You can also read our related guide on questions to ask a mortgage lender before you apply.
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