Mortgage interest rates change every single day — sometimes multiple times a day. Between the time you apply for a mortgage and the day you close, rates can move significantly in either direction. A mortgage rate lock is your protection against that volatility, guaranteeing your interest rate for a set period regardless of what the market does.
Understanding how rate locks work, when to lock, how long locks last, and what options you have if your lock expires is essential knowledge for any homebuyer. This guide covers everything you need to make a confident decision about locking your mortgage rate.
Key Takeaways
- A rate lock guarantees your interest rate for a set period — typically 30 to 60 days.
- Longer lock periods cost more, either through a higher rate or an upfront fee.
- If rates drop after you lock, a float-down option lets you capture the lower rate.
- If your lock expires before closing, you may need to extend it — usually for a fee.
- Lock your rate once you have an accepted offer and are confident in the property.
What Is a Mortgage Rate Lock?
A mortgage rate lock is a lender’s commitment to honor a specific interest rate for a defined period while your loan is being processed. Once locked, your rate will not increase even if market rates rise before closing. Most rate locks are available for 30, 45, or 60 days — enough time to complete underwriting and close on the home.
Rate locks are typically offered after you have a signed purchase agreement and have submitted a complete mortgage application. Locking before you have an accepted offer is generally not advisable, as the lock period may expire before you find a home.
How Much Does a Rate Lock Cost?
Short-term rate locks — 30 days — are usually free. Longer locks cost more, either through a slightly higher interest rate or an upfront fee. The exact cost varies by lender and market conditions.
| Lock Period | Typical Cost | Best For |
|---|---|---|
| 15 days | Free or minimal | Near-closing refinances |
| 30 days | Free | Standard purchases |
| 45 days | Free to 0.10% of loan | Slightly complex transactions |
| 60 days | 0.10% – 0.25% of loan | New construction, complex deals |
| 90+ days | 0.25% – 0.50%+ of loan | Long construction timelines |
When Should You Lock Your Rate?
The ideal time to lock your rate is once you have a signed purchase agreement and are confident the transaction will close. Locking too early risks the lock expiring before closing. Locking too late exposes you to rate increases during underwriting. In a rising rate environment, locking as soon as possible after your offer is accepted is generally the prudent move.
Factors to Consider Before Locking
- Market direction: If rates are rising, lock immediately. If rates are falling, you may benefit from waiting — but this is speculation.
- Closing timeline: Estimate your closing date realistically and choose a lock period that gives you a comfortable buffer.
- Transaction complexity: New construction, short sales, or complex financial situations may require longer lock periods.
What Is a Float-Down Option?
A float-down option is an add-on to a rate lock that allows you to capture a lower rate if market rates drop significantly after you lock. It typically costs an additional 0.25% to 0.50% of the loan amount and requires rates to drop by a minimum threshold — usually 0.25% to 0.50% — before the float-down activates. If you are locking in a volatile rate environment, a float-down option can provide valuable peace of mind.
“Trying to time the mortgage market is like trying to time the stock market — most people get it wrong. Lock your rate when you have a deal you are happy with and focus on closing.” — Senior Mortgage Loan Officer
What Happens If Your Rate Lock Expires?
If your closing is delayed and your rate lock expires, you have two options. You can extend the lock — most lenders offer extensions for a fee, typically 0.15% to 0.30% of the loan amount per 15-day extension. Alternatively, you can let the lock expire and accept the current market rate, which may be higher or lower than your original locked rate. Always communicate proactively with your lender if you anticipate a delay.
| Scenario | What Happens | Your Options |
|---|---|---|
| Rates rise after lock | You keep your locked rate | Proceed — you are protected |
| Rates fall after lock | You are locked at higher rate | Float-down (if available) or accept locked rate |
| Lock expires before closing | Rate reverts to market rate | Extend lock (fee) or accept current rate |
| Deal falls through | Lock is cancelled | Re-lock when new property is found |
FAQ
Can I switch lenders after locking my rate?
Yes, but it comes at a cost. If you switch lenders after locking, you forfeit your rate lock with the original lender and must start the process over with the new lender at current market rates. This is only worth doing if the new lender offers a significantly better rate or terms that outweigh the time and cost of restarting the process. Always compare lenders before locking to avoid this situation.
Does a rate lock guarantee my closing costs too?
A rate lock guarantees your interest rate but not necessarily all closing costs. Some fees — like lender origination fees — may be locked along with the rate, while third-party fees like appraisal and title insurance can still change. Review your Loan Estimate carefully and ask your lender exactly which fees are locked and which may vary before closing.
What is the best time to lock a mortgage rate?
The best time to lock is once you have a signed purchase agreement and are confident the transaction will proceed. In a rising rate environment, lock as soon as possible after your offer is accepted. In a falling rate environment, you might consider waiting briefly — but this is market speculation and carries risk. Most financial advisors recommend locking once you have a rate you are comfortable with rather than trying to time the market.
How long does a mortgage rate lock last?
Standard rate locks last 30 to 60 days, which is sufficient for most home purchases. Longer locks of 90 days or more are available for new construction or complex transactions but typically cost more. Choose a lock period that gives you a comfortable buffer beyond your expected closing date to avoid extension fees.