The best time to lock your mortgage rate is usually when your closing date is close enough that a market swing could hurt you and you cannot recover from it. In practice, that means locking soon after you have a signed purchase contract or a firm refinance plan, with a lock period that covers your lender’s real closing timeline plus a small buffer. Trying to guess the day rates bottom out is far less reliable than matching your lock to your calendar.
This guide walks through how to decide: how lock periods work, how to choose between locking and floating, what extensions cost, and what can quietly void a lock.
TL;DR
- Start with your days to closing, not with a rate forecast. If you close in under 30 to 45 days, locking is generally the safer choice.
- Pick a lock period that matches your lender’s actual closing timeline, not just the date on your contract. The average closing time was reported at 42 days in June 2025.
- Extensions can cost real money, often 0.25% to 1.0% of the loan amount or a flat fee, depending on the lender and the reason for the delay.
- A lock protects your rate only if your application stays the same. A new credit account, a changed appraisal or unverified income can void it.
- Ask about a float-down option before you lock, because it is not standard.
Table of Contents
- What a rate lock does, and what it does not
- Start with your timeline, not the market
- Lock or float: how to decide
- Choosing a lock period that actually covers you
- Rate lock extensions: what they cost and how to avoid them
- What can void a locked rate
- Float-down options
- Disclosures and deadlines after you lock
- Locking when closing is months away
- Our perspective on timing a lock
- Get a rate comparison before you lock
- FAQ
- Sources
What a rate lock does, and what it does not
A rate lock means your interest rate will not change between the offer and closing, as long as you close within the specified time frame and nothing changes in your application. Two parts of that sentence matter: the time frame and the “nothing changes.”
A lock freezes the rate and the points tied to it. It does not approve your loan, and it does not guarantee the property will appraise or that your documents will clear underwriting. It is also not automatic. The CFPB notes that some lenders lock your rate as part of issuing the Loan Estimate, but some do not. If your rate is not locked, it can change at any time. Check the rate lock section of your Loan Estimate so you know which situation you are in.
How long a lock usually lasts
A lock typically runs 30, 45 or 60 days, though shorter and longer periods exist. Longer locks, such as for new construction, can be offered but are sometimes priced a little higher. The reason is simple: the lender is carrying the risk of market movement for more days.
Start with your timeline, not the market
Most lock or float advice begins with a rate prediction. A better starting point is your own calendar. A lock has a term, and extending it costs money, which makes your days to closing the first filter.
Here is a practical framework built on that idea, using the same thresholds the MortgageDaily guide describes:
| Days to closing | Usual posture | Why |
|---|---|---|
| Under 30 | Lock | No time to recover from an adverse move |
| 30 to 45 | Lock in most cases | Short runway, and an extension may be needed if anything slips |
| 45 to 60 | Judgment call | Depends on your risk tolerance and budget cushion |
| Over 60 | Float with a trigger, or lock for a longer term | Set a rate at which you will lock, so you are not deciding emotionally |
These are guidelines, not rules. A buyer with a tight debt-to-income ratio has a different risk than one with room to spare, which brings us to the next question.
Lock or float: how to decide
Floating means you leave your rate unlocked and take whatever is available when you do lock, hoping for a lower rate. Locking means certainty. Industry experts quoted by Kiplinger treat the choice as a matter of risk tolerance and market outlook.
When locking tends to make sense
- Rates have been trending up, or the market is volatile.
- The rate you have been quoted already fits your budget with room to spare.
- You expect to close within the lock period.
- You do not plan any big purchases or credit changes before closing.
When floating can be reasonable
- You expect rates to fall and can absorb a higher payment if you are wrong.
- You are unsure of your closing timeline.
- You are weighing whether to buy discount points to lower your rate.
Floating is a bet, and the downside is not symmetrical. If rates drop a little, you save a little. If they jump while you are inside two weeks of closing, you may have to accept a rate that changes whether the loan still works for you.
A worked example
Say you are borrowing $400,000 on a 30-year fixed loan. By our arithmetic, the principal and interest payment at 6.50% is about $2,528 a month. At 6.75% it is about $2,594, roughly $66 more each month, or close to $800 a year. That is a quarter point. A float that goes wrong by half a point costs about double. Now compare that with a possible extension fee: at 0.25% of $400,000, an extension costs $1,000, and at 1.0% it costs $4,000. Whether to float is a question of whether you can live with either outcome.
The loan terms above are for illustration only. Your payment depends on your actual rate, term, taxes, insurance and any mortgage insurance.
Choosing a lock period that actually covers you
The most common lock mistake is choosing a period based on the contract’s closing date instead of how long your lender really takes. Bankrate advises checking your lender’s average closing timeline and aligning your lock period with it, rather than relying only on the contract date.
Before you lock, ask your loan officer:
- What is your average time from lock to closing right now?
- Does my loan type add steps? FHA, VA, condo and new construction loans can add appraisal or approval steps.
- What does a 15-day, 30-day and 45-day lock cost in rate or points?
- What happens if the seller or the title company delays closing?
If the answers suggest your closing could land near the end of a 30-day lock, a 45-day lock is often cheaper than paying for an extension. You can compare the economics side by side on loan types like the 30-year fixed-rate mortgage or the 15-year fixed-rate mortgage, since the payment impact of a rate change differs by term.
Purchase locks versus refinance locks
On a purchase, your contract sets a closing deadline, so a delay can put the deal at risk, not just the rate. Refinances are usually more flexible, which gives you more room to float with a trigger. If you are refinancing, run your numbers first with the refinance calculator so you know the rate at which refinancing stops paying off. That number is a natural trigger for your lock.
Rate lock extensions: what they cost and how to avoid them
If you do not close before your lock expires, you have two options: extend or relock. Extension fees often range from 0.25% to 1.0% of the loan principal, or a flat fee, depending on the lender and the reason for the delay.
If you let the lock expire, you may face relocking at the worst-case price, meaning the less favorable of your original rate and the current market rate, according to the same Bankrate guide. That is why a buffer matters more than squeezing out the cheapest lock.
Ways to lower the odds you need an extension:
- Respond to underwriting requests the same day.
- Order the appraisal and homeowner’s insurance early.
- Confirm that your title company and seller can hit the closing date.
- Choose a lock length with a few days of cushion.
- Ask who pays if the delay is the lender’s fault. Some lenders cover extensions for their own delays, and others do not, so ask in advance.
What can void a locked rate
A lock is conditional. According to the CFPB, rate locks typically only guarantee your rate if nothing changes about your application. Examples include:
- The home appraises differently than expected.
- A credit-impacting event, such as opening a new credit card.
- Income that cannot be verified, such as bonuses or overtime.
Tell your loan officer about any major financial change right away, before it surfaces in underwriting. Avoid new credit, large purchases on credit and job changes until you have closed. If your situation involves complex income, your loan officer can tell you which loan types document income differently.
Float-down options
Some lenders offer a float-down, which lets you take a lower rate if the market drops after you lock. It is not standard and often requires an additional fee or a specific loan product. Borrowers usually have to request it before closing, and Investopedia notes that it may be exercised as early as a week after the process begins in some cases. Ask before you lock whether a float-down can be added, what it costs, and what rate drop triggers it. If the fee is close to what a likely rate drop would save, skip it.
Disclosures and deadlines after you lock
Locking triggers paperwork. Under the TILA-RESPA Integrated Disclosure rule, if you lock after receiving your initial Loan Estimate, the lender must provide a revised Loan Estimate within three business days of the lock. You must also receive the Closing Disclosure at least three business days before closing. Compare it to your latest Loan Estimate and check that the rate and points match what you locked. If they do not, ask your lender to explain before closing day.
That three-day window is one more reason to plan lock length with a cushion. For a plain-language look at how deadlines drive real estate closings, this overview of closing on time with required documents and deadlines in place shows how missing a document can push a closing date, which is exactly what burns lock days.
Locking when closing is months away
New construction and long closings are the hardest case. If you are more than 60 days out, you can float with a pre-set trigger, for instance “I lock if my rate reaches X,” or pay for a longer lock. Writing the trigger down in advance stops you from chasing headlines. Cash-based deals and fast closings show how much a closing date can vary: some sellers close in 7 to 14 days in Florida, while financed purchases take much longer, so confirm your own timeline in writing before you pick a lock term.
If you are selling one home and buying another, remember the lock-in effect. As of 2024Q2, the average mortgage holder had a rate 2.54 percentage points below the market rate, according to the FHFA. That makes your next rate matter more, and it makes timing your lock around the sale of your current home worth planning.
Our perspective on timing a lock
We see the same pattern with first-time buyers and refinancers: people spend weeks watching rate charts and almost no time checking whether their lock period matches their closing date. We think that is backwards.
Our approach starts with three questions. When do you need to close? How much monthly payment change can your budget absorb? And what would you do if rates moved against you tomorrow? Once those are answered, the lock decision is usually clear.
Because our application is fully online and can lead to funding in under 21 days, we can often help you pair a shorter lock with a realistic timeline. A shorter timeline means fewer days of exposure and less chance you need an extension. We also compare rates across lenders, so you can see what different lock lengths cost before you commit. Every file is different, so we confirm the details for your loan with you in writing.
— David Mordue
Get a rate comparison before you lock
If you are buying or refinancing and want to see your options side by side, you can start a pre-approval or refinance request and ask for lock options at different lengths. Looking at a different loan structure? We also offer FHA loans, VA loans and adjustable-rate mortgages, each with its own timeline considerations. Investors who qualify on rental income can look at DSCR loans.
FAQ
When should I lock my mortgage rate?
For most buyers, lock once you have a signed contract and a closing date within roughly 30 to 45 days. If your closing is more than 60 days away, consider floating with a clear trigger rate or paying for a longer lock. Ask your loan officer what their current lock-to-close time is before choosing.
How much does a rate lock extension cost?
Fees often range from 0.25% to 1.0% of the loan amount or a flat fee, depending on the lender and the reason for the delay. On a $400,000 loan, that is $1,000 to $4,000. Ask your lender for its fee schedule before you lock.
Can I lock my rate before I find a home?
Some lenders allow a lock at pre-approval, but the lock period still starts running, and you may need a long and costlier lock to cover your search. Many buyers wait until they have a contract. Ask your lender how it handles locks before you have a property.
What happens if rates drop after I lock?
Your locked rate stays in place unless you have a float-down option or your lender agrees to renegotiate, which may involve a fee. Float-downs are not standard, so request one in writing before locking if it matters to you.
Can a locked rate change before closing?
Yes, if something material changes in your application, such as the appraisal, your credit or your verified income. The CFPB explains that locks typically hold only if the application is unchanged. Tell your loan officer about any financial change right away.
Sources
- Bankrate: Mortgage Rate Lock Extension Fees
- MortgageDaily: Lock or Float? How to Read Today’s Rate Signal
- Kiplinger: Lock or Float Your Mortgage Rate?
- Investopedia: Mortgage Rate Lock Float Down
- Zillow: When Do I Lock In My Interest Rate?
- CFPB: What’s a lock-in or a rate lock on a mortgage?
- CFPB: Review loan estimates
- CFPB: What if the rate or fees are different on my Closing Disclosure?
- FHFA: The Geography of the Lock-In Effect