The Core Principle
Rate lock rules are lender-specific. There is no Texas law and no universal mortgage rule that sets a lock period, an extension fee, a float-down option, a relock, or a free extension. The written lock agreement and your lender's policy control what happens on your file, and that is the layer this page teaches.
What is a mortgage rate lock in Texas? It is an agreement with your lender that holds a specific interest rate, and usually the points attached to it, for a set number of days. A lock can protect you if rates rise before closing, but the exact length, the cost of an extension, and what happens if your closing date moves are all set by your lender, not by the state.
Every claim below is labeled with the class of source it comes from, so you can see which layer is talking: the written lock agreement, lender policy, common market practice, or professional judgment. Rate-lock pricing changes constantly, so nothing on this page is a current quote or a guarantee.
What a Rate Lock Actually Does
A rate lock is a written agreement between you and one lender. It holds a quoted interest rate, and typically the discount points or lender credits tied to that rate, for a specific period, usually aligned to an expected closing date. If market rates rise during the lock, your locked rate still holds. That is the protection a lock exists to provide.
Source: lender policy / written lock agreement
The lock does not stand alone. It sits inside the whole transaction: your contract's closing date, your financing, your deposit timing, and your rate strategy are all connected. Closing timing can affect rate locks, and a lock that outlives its window is where the costs show up.
Source: common market practice / strategic judgment
What a Rate Lock Does Not Do
A lock is not final approval. It protects a rate, not the loan file. Your loan can still change or fail for property, appraisal, title, insurance, updated credit, income, assets, or underwriting conditions, all independent of the lock. A lock also does not automatically give you a lower rate if market rates drop after you lock. That only happens if your lock includes a float-down option.
A lock is also not set by the TREC contract. The Texas residential contract establishes the closing date and the financing terms, but the lock itself lives entirely with your lender. If someone tells you a lock period or extension policy is required by Texas law, that claim deserves a skeptical look.
Source: lender policy / negotiable term
The same separation applies to the offer side of the deal: a documented financing position can help a seller evaluate execution risk, but it does not guarantee approval. For the difference between a preapproval and final approval, read pre-approval vs pre-qualification.
The Lender-Specific Checklist
Every one of these items is lender-specific. None of them are Texas law or a universal mortgage rule, and each one is a question to ask before you lock:
Lock duration
How many days the lock holds, typically aligned to your expected closing date. Some locks run longer for a higher cost, and some expire before your closing if the calendar slips.
Source: lender policy
Expiration
What happens on the day the lock expires. Some locks roll into a higher rate, some can be extended at a cost, and some carry conditions. Ask for the exact expiration language in writing.
Source: lender policy
Changes in loan or property
A lock usually attaches to a specific loan amount, loan program, property, and occupancy. Change any of them and the locked pricing may change with it. Confirm what triggers a repricing on your file.
Source: lender policy
Extension
Whether the lock can be extended, at what cost, and under what conditions. Some extensions are free within a window, some cost money, and some are not available at all. The written agreement controls.
Source: lender policy
Relock
Whether a new lock can be placed after an expiration, and at what pricing. Relocks typically follow current market pricing, sometimes with an added cost. Ask how a relock would be priced for your scenario.
Source: lender policy
Float-down
A feature on some locks that lets you move to a lower locked rate if market rates drop, often only after a set drop and sometimes for a fee. Not every lock has it, so ask before you lock.
Source: lender policy
Long-term new-construction locks
Special locks for homes still being built, sometimes stretching months past a typical resale lock. Longer locks usually cost more or carry different terms, and they carry builder delay risk built in.
Source: lender policy
Builder delay risk
Construction timelines slip, and a slipped completion date can push past a lock's expiration. How that is handled depends on your lock agreement and lender policy, not on a universal rule.
Source: lender policy
Two of these deserve a closer look, because they are where most buyers get surprised: extensions and new-construction locks.
Extensions: Who Pays If the Lock Expires?
This is the question buyers actually ask: if my closing is delayed and the lock runs out, who pays? The honest answer is that there is no universal answer. The written lock agreement and your lender's policy control. Some locks include a free extension window, some charge a fee, some roll the rate to current market pricing, and some offer a one-time courtesy. All of that is decided before you lock, and the terms are the ones you agreed to.
Don't repeat the myth
"If the builder caused the delay, the lender must extend the lock for free." No universal rule supports that statement. There is no law or agency guideline that forces a lender to extend a lock at no cost just because a delay was not your fault. The written lock agreement and the lender's policy are what control, so read the extension language before you sign the lock.
Source: lender policy / written lock agreement
For the mechanics of extension pricing, read what a rate lock extension costs. And if your closing date itself is slipping, see what to do when closing is delayed, because the fix starts with the contract and the calendar, not just the lock.
New Construction and Long Locks
New construction is where lock timing matters most, because the home is not ready when you sign. Long-term locks exist for exactly this situation, and they usually cost more or carry different terms than a standard resale lock. The tradeoff is real: a longer lock protects you while the home is being built, but it also carries builder delay risk, because a completion date that slips can push past the lock's expiration.
Before you lock on a new build, ask how a construction delay is handled in writing, and confirm whether the builder's completion date is a firm contractual date or an estimate. For the full picture on buying a home under construction, read buying new construction: tips and timing and the San Antonio new construction guide.
Source: lender policy / common market practice
Float-Down and Relock, Briefly
A float-down option lets you lower a locked rate if market rates drop before closing, often subject to a minimum drop and sometimes a fee. A relock is a new lock placed after an old one expires, usually at current market pricing. Both are lender-specific features, not guarantees, and neither is automatic. See what a float-down option is and lock vs float for the details.
When to Lock: The Timing Question
Common practice is to lock once you are under contract and know your expected closing date, so the lock window lines up with the contract calendar. Locking too early risks expiration before closing; waiting too long leaves you exposed to rising rates. Your loan officer's pricing calendar, the loan program, and the expected closing date all feed that decision, which is exactly why it belongs in the deal-structure conversation, not off to the side.
The lock also interacts with the rest of your structure: a rate buydown changes your rate and points, a seller concession can cover some of your costs, and the closing date you negotiate in the contract sets the calendar the lock has to survive. Read seller concessions in Texas and interest rate buydowns explained to see how the pieces fit, and start from the closing-cost list on the closing costs for buyers in Texas page.
Source: common market practice / strategic judgment
Frequently Asked Questions
Who pays if the rate lock expires?
There is no universal answer. The written lock agreement and your lender's policy control. Some locks include a free extension window, some charge a fee, some roll to current market pricing, and some offer a one-time courtesy. Ask what happens at expiration before you lock, and get it in writing.
Is a rate lock required in Texas?
No. A rate lock is an agreement between you and your lender, not something Texas law or the TREC contract requires. Whether and when to lock is a decision you make with your loan officer, and the terms are the ones your lender offers.
What does a rate lock actually cover?
A lock typically holds your rate and the points or lender credits attached to it for the lock period. Inclusions vary by lender, so confirm in writing exactly what is and is not covered, including how changes to the loan amount, program, or property affect the lock.
Can I lock my rate before I make an offer?
Some lenders offer longer or temporary locks so you can secure a rate while you shop, but those locks usually cost more or carry a shorter window and can expire before you are under contract. Ask what happens if you have not gone under contract by the time the lock ends.
Does locking my rate mean I am approved?
No. A lock is separate from approval and underwriting. You can lock while conditions are still being cleared, and final approval still depends on the property, appraisal, title, insurance, updated credit, income, assets, and loan conditions. A lock protects a rate, not the loan file.
The Bottom Line
A rate lock protects a rate, and the rules around it are set by your lender's written lock agreement, not by Texas law. Because the lock is tied to your closing date, the timing conversation is really a deal-structure conversation: the contract calendar, the builder timeline, the extension risk, and the rate strategy all meet in one place. Ask the questions before you lock, and line the lock up with a closing date it can actually survive.
As a loan officer and a Texas REALTOR, I can walk you through the lock and the contract at the same time. I originate mortgages anywhere in Texas and represent buyers in Greater San Antonio and the Texas Hill Country. Bring me your closing date and your scenario, and I will show you the lock terms and the timing that fit your deal before you sign anything.
This page is educational and is not legal, tax, or rate-shopping advice. Lock periods, extension fees, float-down options, and relock terms are lender-specific and change over time, and rate-lock pricing is not published here as a current quote. Confirm the written lock agreement and current pricing with your loan officer before relying on anything on this page. No term on this page is a guarantee.
Lock Your Rate With the Right Questions
Bring me your expected closing date and your contract calendar, and I will walk you through the lock terms, the extension risk, and the timing that fit your deal.
