What is a mortgage rate lock?

A mortgage rate lock is a written commitment from your lender that your interest rate will not change for a set period — typically 30, 45, or 60 days. It protects you from rate increases between application and closing but also prevents you from automatically benefiting if rates drop.

How long should I lock my mortgage rate?

Choose a lock period that covers your expected closing date with at least a 7–10 day buffer. If closing in 30 days, a 30-day lock works. If closing in 45 days, choose a 45-day lock. Delays are common, and an expired lock forces you to either pay for an extension or accept the current market rate.

What does it cost to extend a mortgage rate lock?

Lock extensions typically cost 0.125% to 0.25% of your loan amount per week extended, or the difference between your locked rate and the current market rate — whichever is greater. On a $400,000 loan, one week extension can cost $500 to $1,000.

Can I get a lower rate if rates drop after I lock?

Not automatically. You would need a float-down option, which allows you to capture a lower rate if it falls by a specified amount during your lock period. Float-down options cost extra — typically 0.25% to 0.50% of the loan amount — and are not offered by all lenders.

When is the best time to lock a mortgage rate?

Lock when your loan file is in underwriting, your closing date is confirmed, and you have chosen a lock period with enough cushion for potential delays. Locking too early means paying for a longer lock period. Locking too late creates risk if rates move against you before you close.

When to Lock Your Mortgage Rate and When to Wait

Rate locks expire. If your closing gets delayed and your lock runs out, you either pay to extend it — typically 0.125% to 0.25% of the loan amount per week — or you take whatever rate is available on closing day, which may be significantly higher than what you were quoted.

A rate lock is not the same as a rate approval. You still need to close before the lock expires, and extensions are not free. Most buyers underestimate how often closings run long.

What a Rate Lock Actually Does

When a lender quotes you an interest rate, that quote is good for the conversation. Rates move daily, sometimes multiple times in a day, based on bond market activity. A rate lock is a written commitment from your lender that your rate will not change for a specified period — typically 30, 45, or 60 days — regardless of what the market does.

In exchange, you give up the ability to benefit if rates drop during the lock period (unless your lender offers a float-down option, which usually costs extra). The lock protects you from rate increases; it also prevents you from automatically capturing decreases.

You cannot lock a rate before you have a signed purchase agreement or an accepted application. Locks are tied to a specific loan, property, and borrower profile.

How Long Rate Locks Last and What They Cost

Standard lock periods are 30, 45, and 60 days. Most lenders offer a 30-day lock for free — meaning the rate they quote already assumes a 30-day lock. Longer locks cost more because the lender is taking on more market risk to hold that rate.

A 45-day lock typically adds 0.05% to 0.10% to your rate. A 60-day lock adds 0.10% to 0.25%. On a $400,000 loan, a 0.25% rate increase equals roughly $67 more per month — about $24,000 over the life of a 30-year loan.

Extensions, if you need them, are priced similarly: 0.125% to 0.25% of the loan amount per week extended, or the rate difference if market rates have moved against you. Neither is cheap.

The Right Time to Lock Based on Your Closing Timeline

The answer is not “lock as early as possible.” The answer is: lock when you have enough certainty about your closing date to choose a lock period that covers it with a 7–10 day buffer, at the lowest cost.

If you are buying and expect to close in 30 days, a standard 30-day lock makes sense. If your closing is scheduled for 45 days out, choose a 45-day lock — do not try to time a 30-day lock hoping for no delays. One appraisal problem, one title issue, or one slow underwriter can push your closing by two weeks.

If you are refinancing, you generally have more control over the timeline and can close faster than a purchase. A 30-day lock is often sufficient for refinances with no complications.

Lock when you have a firm closing date, your loan file is complete and in underwriting, and you have reason to believe rates may move against you before closing. If the market is calm and you expect a smooth close, waiting an extra week to confirm timing before locking can save you from paying for an unnecessarily long lock.

The most expensive rate lock mistake is choosing a period that is just barely long enough. Build in a cushion. A two-week delay on a purchase is not unusual, and an expired lock is a crisis.

What Happens If Rates Drop After You Lock

You are bound to the locked rate unless your lender offers a float-down provision. A float-down option allows you to capture a lower rate if rates fall by a specified amount — typically 0.25% or more — during the lock period. Float-down options cost extra, usually 0.25% to 0.50% of the loan amount added upfront.

Whether a float-down is worth it depends on your read of the rate environment. If rates are falling steadily, a float-down provides insurance. If rates are volatile or rising, the option cost is hard to justify.

One path buyers take in a falling-rate environment: wait to lock until closer to closing, accepting the risk that rates could also rise. This only makes sense if you have a clear read on your closing timeline and the rate risk feels manageable against a potential savings.

If your rate lock expires before you close, contact your lender immediately. Most lenders will extend your lock at current market pricing, which may be higher than your original lock. Some lenders offer a split extension where the borrower and lender each absorb half the rate difference. Ask about this specifically — it is not always offered automatically.

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