Lock Periods, Extensions, Float-Down, Timing Strategy
Mortgage Rate Lock: How It Works, When to Lock, and What Extensions Cost
Lock your rate as soon as you have an accepted offer and a lender you trust. Every day you wait is a gamble. A 0.25% rate increase on a $400,000 loan costs $65/month — $23,400 over 30 years. The cost of locking early and paying an extension if needed is trivially small compared to the cost of a rate increase you did not protect against.
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How Rate Locks Work
- What locks: Interest rate and any associated discount points are frozen for a specified number of calendar days
- What does not lock: Closing costs, third-party fees, and prepaid items are not part of the rate lock agreement
- Written confirmation: Always get the lock in writing — verbal locks are not binding and cannot be enforced
- Action: Lock confirmation should specify: rate, points, lock date, expiration date, and extension policy
Lock Periods
- 30-day: Standard for straightforward purchases closing within 25 days — lowest rate premium available
- 45-day: Best choice for most purchases — enough cushion for common delays without significant rate premium
- 60-90 day: For complex transactions — adds 0.0625–0.25% to the rate compared to a 30-day lock
- Action: Match lock period to your expected closing timeline plus a 5–7 day buffer for unexpected delays
Extensions
- Cost: 0.125–0.25% of loan amount per 7–15 day extension period — $437–$875 on a $350,000 loan
- Lender-caused delay: Negotiate to have the lender cover the extension cost if their processing caused the delay
- Borrower-caused delay: Late documents or renegotiation delays typically mean the borrower pays for the extension
- Action: Request extensions before the lock expires, not after — expired locks may require re-locking at current market rates
Float-Down
- What it is: Option to take advantage of rate decreases after locking — if rates drop below your locked rate by 0.25–0.50%
- Cost: 0.125–0.25% upfront or built into a slightly higher locked rate — some lenders do not offer it at all
- When to ask: Before locking — adding a float-down after the lock is usually not possible with most lenders
- Action: Worth the cost in volatile rate environments where rates could move significantly during your lock period
Frequently Asked Questions
When should I lock my mortgage rate?
What happens if my rate lock expires?
Can I change lenders after locking a rate?
The Bottom Line Up Front
Lock your rate as soon as you have an accepted offer and a lender you trust. Every day you wait is a gamble that rates could move against you. A 0.25% rate increase on a $400,000 loan costs $65 per month — $23,400 over 30 years in additional interest payments.
The cost of locking early and paying a rate lock extension if closing is delayed ($500–$1,000) is trivially small compared to the cost of absorbing a rate increase you failed to lock against. Get the lock confirmation in writing with the rate, points, expiration date, and extension policy clearly stated. Ask about float-down options before committing to the lock. And understand that a verbal lock from a loan officer is not binding — only a written confirmation protects you.
How Does a Mortgage Rate Lock Work?
When you lock your rate, the lender freezes your interest rate and any associated discount points for a specified number of calendar days. During that lock period, your rate does not change regardless of what happens in the broader bond market or with Federal Reserve policy. If mortgage rates rise 0.5% during your lock period, your rate stays at the locked level. If rates fall 0.5%, your rate also stays locked — unless you negotiated a float-down provision before locking.
The lock applies to the interest rate and points only. Closing costs, third-party fees (appraisal, title, recording), and prepaid items (taxes, insurance, per-diem interest) are not part of the rate lock and are finalized separately on the Closing Disclosure. The written rate lock confirmation from the lender should specify: the locked interest rate, any discount points, the lock initiation date, the lock expiration date, and the extension policy including cost per extension period.
Deal Saver
Always get your rate lock confirmation in writing — email confirmation or a document on the lender’s secure portal. A verbal lock from a loan officer during a phone call is not legally binding and cannot be enforced if there is a dispute. The written confirmation is your proof of the locked terms. It should show the exact rate, the points (if any), the lock date, the expiration date, and any float-down terms you negotiated. No written confirmation means no enforceable lock — treat verbal promises as meaningless regardless of who made them.
How Do You Choose the Right Lock Period?
The lock period should match your expected closing timeline plus a 5–7 day buffer for unexpected delays. A 30-day lock works for straightforward purchase transactions where you expect to close within 25 days. A 45-day lock is the safest and most commonly recommended choice for typical purchases — it provides enough cushion for common delays (appraisal scheduling, underwriting conditions, title issues) without carrying a significant rate premium over the 30-day lock.
Longer lock periods cost more because the lender takes on additional interest rate risk for a longer duration. A 60-day lock typically runs 0.0625–0.125% higher in rate compared to a 30-day lock. A 90-day lock adds 0.125–0.25% to the rate. For new construction with 6-month or longer build timelines, extended locks of 120–180 days are available through some lenders but carry substantial premiums of 0.25–0.375% above the standard 30-day rate — effectively adding tens of thousands of dollars over the loan term in exchange for rate certainty during the construction period.
| Lock Period | Rate Premium vs 30-Day | Best For |
|---|---|---|
| 30 days | Baseline (lowest rate) | Straightforward closings within 25 days |
| 45 days | +0.0–0.0625% | Most purchases — recommended default choice |
| 60 days | +0.0625–0.125% | Complex transactions, condo projects, title issues |
| 90 days | +0.125–0.25% | New construction nearing completion |
| 120–180 days | +0.25–0.375% | New construction with 4–6 month build timeline |
What Do Rate Lock Extensions Cost?
If your closing is delayed past the lock expiration date, you need a rate lock extension. Extension costs are typically 0.125–0.25% of the loan amount per 7–15 day extension period. On a $350,000 loan, a single extension costs $437–$875. Some lenders offer a flat fee structure instead — $500 per extension regardless of loan size.
If the delay was caused by the lender — underwriting processing delays, documentation errors, appraisal scheduling failures, or compliance review backlogs — you have strong grounds to negotiate having the lender absorb the extension cost entirely. If the delay was caused by you — late document submissions, inspection renegotiation that required additional time, or scheduling conflicts — you typically pay the extension fee. Document the cause of any delay in writing as it occurs during the process — this documentation determines who is responsible for extension costs if the lock period runs short.
Lender Reality Check
Some lenders quietly let locks expire and then re-lock at the current (often higher) market rate — telling the borrower their lock expired so the rate went up. This is preventable: track your lock expiration date on your calendar, request extensions before the lock expires rather than after, and hold the lender accountable for processing delays they caused. A lender that blames you for their own processing failures and then charges you for a rate lock extension is a lender you should not be working with on any transaction.
What Is a Float-Down Provision?
A float-down option lets you capture a lower rate after locking if market rates decrease below your locked rate by a specified threshold — typically 0.25–0.50%. When triggered, you receive a new rate that is either the current market rate or a rate between your locked rate and the new market rate, depending on the lender’s specific float-down terms.
Float-down options are not free. Some lenders charge 0.125–0.25% upfront for the option at the time of locking. Others build a small premium into the initial locked rate to cover the float-down risk. And some lenders do not offer float-down provisions at all — they are not universally available. Ask about float-down options before you lock the rate — adding a float-down after the lock is executed is usually not possible. In volatile rate environments where rates could move significantly in either direction during your lock period, the float-down premium is often worth paying for the downside protection it provides.
When Should You Lock Your Rate?
The optimal time to lock is when you have an accepted offer, a chosen lender, and reasonable confidence that closing will happen within the lock period you select. Trying to time the rate market — waiting for rates to drop before locking — is speculation, not strategy. Professional mortgage traders with billions of dollars in resources cannot reliably predict short-term rate movements. You should not try either.
The risk calculation strongly favors locking early. If rates drop after you lock, you lose the potential improvement (unless you have a float-down) but your payment stays at the rate you budgeted for. If rates rise after you fail to lock, your payment increases for the life of the loan. The downside of locking too early (missed rate improvement) is bounded and temporary. The downside of locking too late (permanent rate increase) compounds over 30 years of payments. Lock when you have the offer and the lender — do not gamble on market timing with the largest financial commitment of your life.
What Are Lock-and-Shop Programs?
Some lenders offer lock-and-shop programs that let you lock a rate before you have an accepted purchase offer. You lock the rate based on an assumed loan amount and property type, then have 60–120 days to find and close on a home. If the actual property and loan terms differ from the initial lock assumptions, the rate may adjust slightly — but you are protected from major market-driven rate increases during your home search.
Lock-and-shop programs are valuable in competitive purchase markets where the home search may take months and rate uncertainty adds stress to an already stressful process. The tradeoff is a slightly higher rate compared to a standard lock (the lender charges a premium for the extended uncertainty period) and the commitment to that specific lender. If you switch lenders after a lock-and-shop, you lose the locked rate. These programs work best when you are working with a lender you trust and expect to close with regardless of which property you ultimately purchase.
File Guidance
Before locking, ask your loan officer these four questions: (1) What is the rate and points for a 30-day versus 45-day lock? (2) What is your extension policy and cost per extension period? (3) Do you offer a float-down provision, and what does it cost? (4) What happens if the lock expires because of a delay you caused? The answers to these four questions tell you everything you need to know about whether the lender handles rate locks fairly or uses them as a profit center at the borrower’s expense.
The Bottom Line
Lock your rate when you have an accepted offer and a lender you trust — do not gamble on rate movements. Choose a 45-day lock for most purchases as the safest default. Get the lock in writing with the rate, points, expiration, and extension terms clearly documented.
Ask about float-down provisions before locking if you want downside protection against rate decreases during the lock period. Track your expiration date and request extensions before the lock expires, not after. If the lender caused the delay, negotiate to have them cover the extension cost. The cost of locking early is small. The cost of not locking and watching rates rise is permanent.
Frequently Asked Questions
Is a rate lock free?
Standard 30–45 day locks are typically free (the cost is built into the quoted rate). Longer locks (60–180 days) carry explicit rate premiums. Float-down options cost 0.125–0.25% extra. Extensions cost 0.125–0.25% per period. The base lock itself has no separate out-of-pocket fee.
Can I lock with multiple lenders?
Technically yes, but you can only close with one. Some lenders require a credit card or deposit to lock, which you forfeit if you do not close with them. Locking with multiple lenders simultaneously is unusual and generally not recommended — compare Loan Estimates first and lock with the best offer.
What if rates drop significantly after I lock?
If you have a float-down provision, you can capture the lower rate per the provision terms. Without a float-down, you are locked at the original rate. Some borrowers cancel and re-lock, but this restarts the process and the lender may not offer a lower rate. The float-down is the cleanest solution for this scenario.
How long should I lock for a refinance?
30–45 days for most refinances. Since there is no purchase contract deadline, refinance timelines are more flexible. However, longer timelines increase the risk of rate changes if you need to re-lock. Ask your lender about their average refinance closing time to choose the right lock period.
Does the lock transfer if my loan is sold?
The lock is between you and the originating lender. If the loan is sold to a different servicer after closing, your locked rate is already permanent — the sale does not affect your terms. Pre-closing loan transfers (rare) would require the new lender to honor the original lock terms.
Can I renegotiate my locked rate?
Generally no — a lock is a mutual commitment. However, if market rates drop significantly and you have a strong relationship with the lender, some will offer a one-time courtesy re-lock at a lower rate to retain your business. This is not guaranteed and entirely at the lender’s discretion.