Rate Lock: What It Is and How Long You Should Lock
Last updated: October 2026 · Editorial standards
Mortgage interest rates change daily — sometimes multiple times a day. A rate lock protects you from rate increases between your application and closing. Here’s how they work and how to use them strategically.
What Is a Mortgage Rate Lock?
A rate lock is a lender’s written commitment to hold a specific interest rate for a defined period — typically 30 to 60 days — regardless of market movements.
Without a rate lock, your final interest rate isn’t determined until closing. If rates rise 0.5% in the two months it takes to close, your monthly payment increases and your purchasing power shrinks.
A rate lock gives you certainty.
When Can You Lock Your Rate?
Most lenders allow you to lock after you have a signed purchase contract on a specific property. Some allow locks at pre-approval.
You typically cannot lock a rate until you have a specific property under contract because the lock is tied to the loan (property, amount, term).
How Long Should You Lock?
The most common lock periods:
- 30-day lock: Shortest and cheapest. Only feasible if closing is imminent.
- 45-day lock: Standard for many purchase transactions.
- 60-day lock: Common in today’s market where closings can take longer.
- 90-day lock: For construction or complex transactions. Higher cost.
The golden rule: Lock for at least as long as you expect the closing to take — plus a buffer.
Example: You expect to close in 40 days. Lock for 60 days to give yourself a 20-day cushion. Running out of lock and needing an extension is expensive.
How Much Do Longer Locks Cost?
Longer locks cost more. The rate premium for longer locks:
- 30-day lock: baseline rate (lowest)
- 45-day lock: +0.0–0.125% (varies)
- 60-day lock: +0.125–0.25%
- 90-day lock: +0.25–0.5% or more
Alternatively, some lenders charge a fee rather than a rate premium for longer locks.
What Happens If the Rate Lock Expires?
If your lock expires before closing, you have two options:
1. Lock extension: Pay a fee to extend the lock (typically 0.1–0.25% of the loan amount for each 7–15 day extension).
2. Re-lock at current market rate: If rates have dropped, this could be beneficial. If rates have risen, you lose the protection you paid for.
Prevention: Choose a long enough lock period. Better to pay a small premium upfront than rush a closing or pay extension fees.
Float Down Options
Some lenders offer a “float down” provision for an additional fee. A float down lets you capture a lower rate if rates decrease after you lock, while still protecting you if rates rise.
Float down conditions:
- Rates must drop by a minimum amount (often 0.25–0.5%) before you can use the float down
- You can typically exercise it only once
- Additional fee: usually 0.1–0.5% of loan amount
Float downs are most useful in volatile rate environments. Evaluate the cost versus the probability of rates dropping enough to trigger it.
What to Watch During the Lock Period
Once locked, avoid anything that could change your loan terms:
- Don’t take on new debt (car loans, credit cards)
- Don’t change jobs or reduce income
- Don’t make large unusual deposits without documentation
- Don’t buy appliances or furniture on credit before closing
Changes in your financial profile can trigger re-underwriting — which could change your rate or qualification status.
Rate Lock vs. Rate Float: When to Float
Sometimes it makes sense to “float” — not lock — and wait for a better rate.
When floating makes sense:
- You expect rates to decline based on economic signals (Fed rate cuts, weakening jobs reports)
- Your closing is far away and a long lock is expensive
- You’re willing to accept the risk of rates rising
When locking makes sense:
- Rates are favorable relative to your needs
- You can’t afford a higher rate without losing the ability to qualify
- The market is volatile and rate certainty has high value to you
Most homebuyers are better served by locking — the certainty is worth a small premium.
Key Takeaways
Lock as soon as you have a purchase contract and the rate is acceptable to you. Choose a lock period with a comfortable buffer beyond your expected closing date. Don’t try to time rates — the upside of floating rarely justifies the risk for owner-occupant buyers.
Frequently Asked Questions
Can I lock a rate before finding a home? Some lenders offer pre-approval locks or “lock and shop” programs, though these are less common and often carry higher rates or fees.
What if my closing is delayed through no fault of mine — does the lender extend free? Some lenders extend the lock at no cost if the delay is caused by their processing. If caused by the seller or title issues, you typically still pay extension fees. Ask your lender upfront what their policy is.
Can I change lenders after locking? Yes, but you lose your lock. The new lender will lock at whatever current rates are. Only change lenders if the improvement in rate or terms clearly justifies the cost.
Does a rate lock guarantee I’ll get that rate? Yes — as long as your financial profile doesn’t change materially and you close within the lock period. If your credit drops, income changes, or the property appraises low, the lender may adjust terms.
