A mortgage rate lock is a lender's commitment to hold your interest rate and pricing for a set number of days while your loan closes. Most buyers lock once they're under contract and have a closing date, and they pick a lock period that covers that date with some room to spare. Locks commonly run 30 to 60 days, and longer locks usually cost more. If a lock expires before you close, you'll typically need to pay to extend it or relock under the lender's policy, which can mean worse pricing.
That's the short version. The details matter more than most people expect, especially if you're relocating, buying new construction or selling one home while buying another, because those closings often take longer than a standard purchase.
I'm Paul Mattos, a mortgage broker in Fort Mill, SC, licensed in North and South Carolina. Here's how rate locks work and how I help buyers time them.
What a Rate Lock Actually Covers
A lock holds the rate and the pricing for a specific loan scenario. Pricing means any discount points you pay or lender credits you receive at that rate.
The lock is tied to the details of your loan, including:
Loan program and term
Loan amount and purchase price
Loan-to-value, which depends on your down payment and the appraised value
Credit score
Occupancy, such as primary home, second home or investment property
Property type, such as single-family, townhome or condo
Lock period and expiration date
If one of those changes after you lock, your pricing can change too, even though you're locked. For example, a lower appraisal, a lower credit score on an updated report or a switch from one loan program to another can all change the price of the same rate. A lock protects you from market movement. It doesn't protect you from changes to your own file.
When Can You Lock?
Most of the time, you lock once you have a signed purchase contract and a property address, because the lock is tied to a specific property and closing date.
Some lenders offer programs that let you lock before you find a home. These vary a lot by lender, often come with conditions and may cost more, so ask before you count on one.
As a mortgage broker, I lock your loan with the wholesale lender we choose. Once you're locked with that lender, moving to a different lender usually means starting a new lock at that lender's pricing.
How Long Should Your Lock Be?
Pick a lock period that covers your contract closing date plus a buffer for normal delays. Common options are 15, 30, 45 and 60 days, and many lenders offer longer locks too.
In general:
Shorter locks usually have better pricing, but leave less room for delays.
Longer locks usually cost more, through a slightly higher rate or higher points, but give you more breathing room.
In North Carolina, buyers usually line up the lock with the due diligence period and the closing date in the contract. Inspections, the appraisal, insurance quotes and much of underwriting happen during due diligence, so the timeline needs to be realistic from day one.
Floating vs. Locking
Floating means you haven't locked yet, so your rate moves with the market until you do. Rates can go up or down while you float, and no one can reliably predict which way they'll move.
Floating can make sense if your closing is far off and a long lock would be expensive. Locking makes sense when you want certainty about your payment, or when your budget is tight enough that an increase would be a problem. I'll explain the tradeoffs for your timeline, but the decision is yours.
What Is a Float-Down?
Some lenders offer a float-down option. If rates improve after you lock, it lets you lower your rate once, usually by a minimum amount and within a set window before closing.
Float-downs aren't automatic. Some lenders don't offer them, some charge for them, and the rules vary. If a float-down matters to you, ask about it before you lock, not after rates have dropped.
What Happens If Your Lock Expires?
If you can't close before your lock expires, you generally have two options:
Extend the lock. Most lenders charge an extension fee for each set number of days, and the fee usually goes up the longer the extension.
Relock. If the lock fully expires, many lenders apply a relock policy, which can mean you get the worse of your original pricing or current market pricing.
Common reasons a lock runs out include appraisal delays, title or survey issues, repairs the lender requires, slow document turnaround, a closing date that gets pushed back and new-construction delays.
You can help avoid an expired lock by:
Getting fully pre-approved before you make an offer
Sending requested documents quickly
Scheduling inspections and ordering the appraisal early
Shopping homeowners insurance as soon as you're under contract
Choosing a lock period with a realistic buffer
Your Revised Loan Estimate After You Lock
Federal rules require the lender to send you a revised Loan Estimate within three business days after you lock, if your earlier Loan Estimate was based on a floating rate. You can read the rule in 12 CFR 1026.19.
Also ask for a written lock confirmation that shows the rate, the points or credits, the lock period and the exact expiration date. Keep it with your closing paperwork.
Rate Locks for New Construction
New construction is where rate locks get tricky. A to-be-built home can take months, and a standard lock won't cover that.
Here's what to know:
Extended locks let you lock for a longer period, sometimes many months. They usually cost more, and some require an upfront fee. Ask whether that fee is refundable or credited at closing.
Floating until closer to completion is another option. Many buyers float until the builder can give a reliable completion date, then lock for a standard period.
Builder incentives are often tied to using the builder's preferred lender and may include a rate lock or a buydown. Compare the full offer, not just the rate. A mortgage offer review can help you compare side by side.
Delays happen. Weather, permits and inspections can push completion back, so build extra time into any lock.
My new construction loans page covers financing for to-be-built and custom homes.
Rate Locks When You're Relocating or Selling First
If you're moving to the Charlotte area or selling one home while buying another, the timing gets more complicated:
Two closings. If your purchase depends on selling your current home, a delay on the sale can push back your purchase and your lock. Plan for it.
A job offer letter. If you're qualifying with an offer letter, the job's start date and your closing date both need to fit the loan program's rules.
Long-distance closings. Arranging a remote or mail-away signing can take extra time, so set it up early.
For more on timing, read buying in Charlotte before selling your home in another state, Can I buy a house before selling mine? and my Moving to Charlotte mortgage guide.
Your Rate Lock Checklist
Before you lock, make sure you know:
Your loan program, loan amount and down payment
The rate and any points or lender credits
The lock period and the exact expiration date
Your contract closing date and how much buffer you have
The extension cost and the relock policy
Whether a float-down is available, and its rules
What could change your pricing after you lock
That you'll get a written lock confirmation and a revised Loan Estimate
Frequently Asked Questions
When should I lock my mortgage rate?
Most buyers lock once they're under contract and have a closing date. If your closing is months away, like with new construction, you may float until you have a reliable date or use an extended lock.
How long does a rate lock last?
Common lock periods are 15, 30, 45 and 60 days, and many lenders offer longer locks for new construction. Longer locks usually cost more.
Can my rate change after I lock?
Your rate is protected from market changes during the lock, but your pricing can change if your loan details change, such as the loan amount, appraised value, credit score, occupancy or loan program.
What happens if my rate lock expires?
You'll usually need to pay to extend it or relock under the lender's policy, which may mean worse pricing. Choosing a realistic lock period and moving quickly on documents helps you avoid that.
Can I switch lenders after I lock?
You can, but the new lender will need a new lock at its own pricing, and switching late can delay closing. It's best to compare offers before you lock.
Does locking my rate cost money?
A standard lock is usually built into your pricing rather than charged as a separate fee. Longer locks, extensions, float-downs and some new-construction locks can cost more. Ask for those costs in writing.
Get Help Timing Your Lock
Choosing when to lock and for how long depends on your contract, your closing date and how much risk you're comfortable with. I'll walk you through the options and the costs before you decide, especially if you're relocating, buying new construction or selling first. Schedule a consultation or start your application, and see how to get pre-qualified and pre-approved in Charlotte to get started.
Paul Mattos
Mortgage Broker | Refine Mortgage
Carolina Home Financing
NMLS# 2339069 | Licensed in NC and SC
Call or text: 980-221-4959
Email: paulm@refinemortgage.net
Refine Mortgage Inc. | NMLS# 2417960 | Equal Housing Lender. This article provides general educational information and is not a commitment to lend, a rate quote, or an offer to lock a rate. Rate lock terms, periods, extension costs and float-down options vary by lender and loan program and can change. Financing is subject to credit, income, assets, appraisal, title and underwriting requirements. Not all applicants will qualify.
