Mortgage Rate Lock: How It Works and When to Lock Your Rate

Table of Contents

• What Is a Mortgage Rate Lock?
• How a Rate Lock Works
• Rate Lock Periods: 30, 45, 60, 90 Days
• What a Rate Lock Costs
• The Float-Down Option
• When Should You Lock Your Rate?
• What Can Still Change After You Lock
• What Happens If Your Lock Expires
• Frequently Asked Questions

What Is a Mortgage Rate Lock?

A mortgage rate lock is a written agreement between you and your lender that guarantees a specific interest rate for a defined period of time. Once you lock, that rate won’t increase even if market rates rise — as long as you close within the lock period and your loan application details don’t change materially.

Mortgage rates can move daily, sometimes multiple times in a single day, in response to economic data, Federal Reserve decisions, bond market movements, and global events. Between the day you apply and the day you close on a home, rates can shift meaningfully. A rate lock eliminates that uncertainty and lets you budget your mortgage payment with confidence.

The Consumer Financial Protection Bureau notes that your Loan Estimate will state whether your rate is locked, but won’t include detailed information about extension costs or lock duration options — questions worth asking your lender directly.

How a Rate Lock Works

Here’s a typical sequence of events:

• You submit a mortgage application and receive a Loan Estimate with an interest rate quote.
• After reviewing the terms, you request a rate lock from your lender — usually after signing a purchase agreement with the seller.
• Your lender issues the lock in writing, specifying the rate, lock period, and expiration date.
• Your loan goes through underwriting. As long as you close before the lock expires and nothing material changes on your application, you get that rate.
• The lock fee (if any) is typically paid at closing, not upfront.

Important: a rate lock is not the same as mortgage approval. Your lender still verifies income, employment, credit, assets, and the property appraisal during underwriting. Locking your rate doesn’t guarantee your loan will close — it only guarantees the rate if it does.

Rate Lock Periods: 30, 45, 60, 90 Days

Most lenders offer rate locks in standard windows. The most common options are:

The typical purchase mortgage takes 30 to 45 days from application to close. A 45 or 60-day lock provides a comfortable buffer for most transactions. If you’re buying new construction, closing timelines can stretch to 90 days or more, and some lenders offer extended locks specifically for builders.

When choosing a lock period, err slightly longer rather than shorter. The cost of a lock extension is often higher than the marginal fee for choosing 60 days over 45 upfront — and it removes the stress of racing a deadline at closing.

What a Rate Lock Costs

For standard 30- and 45-day locks, many lenders offer them at no direct charge — the cost is factored into the interest rate itself. Longer locks typically either cost a flat fee or result in a slightly higher quoted rate.

When lock fees are charged as a percentage, they typically run 0.25%–0.50% of the loan amount. On a $400,000 mortgage, a 0.25% lock fee equals $1,000. Whether paying for a longer lock is worth it depends on how much you value the certainty and what your closing timeline looks like.

Some lenders advertise “free” rate locks, but recognize that no lock is truly free — the cost is built into the rate you’re offered rather than charged separately. The best approach is to compare lenders on APR (which incorporates fees), not just the stated rate, and ask each lender explicitly about their lock terms and costs.

The Float-Down Option

A float-down option is an add-on to a rate lock that lets you capture a lower rate if market rates fall after you’ve locked. Without it, a standard rate lock is bilateral: you’re protected from increases, but you don’t benefit from decreases.

How float-downs typically work:

• You lock at today’s rate with a float-down provision.
• If rates drop by a specified threshold (often 0.25%–0.50%) before closing, you can exercise the float-down to receive the lower rate.
• If rates rise, your locked rate holds.

Float-down options typically add 0.5%–1.0% to your closing costs or a small rate premium. They’re most valuable in volatile or declining rate environments. In the current 2026 rate environment — where most forecasters expect rates to remain in the low-to-mid 6% range or drift modestly lower — a float-down can provide meaningful protection without giving up the security of a lock.

When Should You Lock Your Rate?

This is the question most homebuyers stress over. The honest answer: no one — not economists, not lenders, not financial journalists — can perfectly time the rate market. The goal isn’t to catch the absolute lowest rate; it’s to eliminate uncertainty once you’ve found terms you can budget around.

Practical guidance for when to lock:

• Lock after going under contract. Most lenders won’t process a lock until you have a signed purchase agreement. This is generally the right time — you have a defined closing date to work backward from.
• Lock when you’re comfortable with the payment. If the rate offered today results in a monthly payment that fits your budget, that’s a compelling reason to lock — regardless of what rates might do next week.
• Watch for volatility signals. Economic uncertainty, inflation data surprises, and geopolitical events can push rates quickly in either direction. In volatile periods, locking earlier provides more protection.
• Don’t wait to time the market. Chasing a lower rate that may never arrive is a gamble. Borrowers who delay locking sometimes see rates move against them before they act.

If you’re still shopping for a home, ask your lender about “lock and shop” programs that let you lock a rate before you’ve found a property. These typically cost more and have specific terms, but can provide peace of mind in a rising-rate environment.

For context on where rates are today and where they may go, see our 2026 mortgage rate forecast. You can also compare live rates at our mortgage rate comparison page.

What Can Still Change After You Lock

A rate lock isn’t airtight. Your locked rate can still be revised — or voided — if material changes occur to your application:

• Credit score changes. New credit inquiries, missed payments, or large new debt taken out after locking can trigger a rate revision. Don’t apply for new credit cards, finance a car, or make large purchases on credit between application and closing.
• Income documentation problems. If your lender can’t verify overtime, bonus income, or self-employment income as stated, your qualification profile changes.
• Home appraisal. If the appraisal comes in lower than expected, your loan-to-value ratio changes, which can affect your rate.
• Loan amount or down payment changes. Shifting your down payment percentage or loan amount can alter your rate tier.
• Property issues. Certain property types or conditions can affect loan eligibility and terms.

The safest strategy: treat your finances as frozen between your rate lock and closing. Avoid job changes, new loans, large cash deposits or withdrawals, and any financial moves your loan officer hasn’t explicitly approved.

What Happens If Your Lock Expires

If your closing is delayed and your rate lock expires before you close, you have two options: extend the lock or let it expire and re-lock at the current market rate.

Extensions typically cost a fee — often 0.25%–0.375% of the loan amount per 15-day extension period, though terms vary significantly by lender. Some lenders offer a one-time complimentary extension if the delay is on their end (for example, if underwriting takes longer than expected).

If rates have dropped since your lock expired, re-locking at the lower rate may actually benefit you — though you’ll need to weigh the delay cost against the rate savings. If rates have risen, extending at cost is usually better than starting over at a higher rate.

To avoid extension situations, choose a lock period that’s realistically longer than you expect to need, communicate proactively with your lender and real estate agent about the timeline, and respond immediately to any documentation requests from underwriting.

Frequently Asked Questions