Mortgage rates move daily, and sometimes hourly. A rate lock is how you stop that movement while your loan gets finished.
What does a lock actually do?
The CFPB’s definition is one sentence. A lock “means that your interest rate won’t change between the offer and closing, as long as you close within the specified time frame and there are no changes to your application.”
Read the second half again. A lock is a conditional promise, not an unbreakable one.
If your rate is not locked, it is floating, which means it “can go up or down” until you lock it or close.
How long do locks last?
Usually 30, 45, or 60 days, “and sometimes longer,” according to the CFPB. The right length is the one that comfortably covers your real closing date.
The agency’s advice is to plan ahead: “If you are concerned that your rate lock period might be too short, ask your lender about switching to a longer rate-lock period now.”
Longer locks generally cost more, and short locks risk an extension fee. There is no free version of this choice.
Can my locked rate still change?
Yes. The CFPB lists concrete triggers.
You changed the loan type or your down payment. The appraisal came back higher or lower than expected. Your credit score moved, maybe because you opened a new account or missed a payment. Or the lender could not document your overtime, bonus, or other income.
When any of those happen, the lender issues a revised Loan Estimate with new numbers.
So do not open a credit card, finance furniture, or change jobs between the lock and the closing table. A lock does not protect you from yourself.
What is the downside of locking?
You give up the upside. The CFPB says plainly that “a rate lock may lock you out of a lower interest rate if rates fall after you get your loan offer.”
It also warns that a lock “may be expensive to extend if your transaction needs more time.” Delays are common, and the fee lands on you.
What about a float-down?
Some lenders offer a feature that lets you take a lower rate once if the market drops before closing. The industry calls it a float-down.
Be careful with that term. The CFPB does not define it anywhere. It does not appear in the agency’s rate lock FAQ, its Loan Estimate explainer, its Closing Disclosure explainer, or its full Home Loan Toolkit.
That means a float-down is an industry term for a lender specific product, not a standard protection you are owed. Its trigger, its fee, and how many times you can use it are all set by the lender.
The CFPB does suggest the underlying question. It tells borrowers to ask their lender: “If I lock my rate, and interest rates go down, what happens?” Get the answer in writing before you rely on it.
What should I ask before I lock?
The CFPB publishes the list. Use it word for word.
What does it mean if I lock my rate today? What rate lock time frame does this Loan Estimate provide? Is a shorter or longer rate lock available, and at what cost? What if my closing is delayed and the rate lock expires? If I lock my rate, are there any conditions under which my rate could still change? If I lock my rate, and interest rates go down, what happens?
What this means for you
Check page 1 of your Loan Estimate. It shows whether your rate is locked and until what date and time. Some lenders lock when they issue the form and some do not.
Match the lock window to your contract, then add a buffer. A 30 day lock on a 45 day closing is a fee waiting to happen.
Remember what is at stake each month. On this $320,000 loan at 6.5%, principal and interest are $2,023, and the loan costs about $411,342 over 30 years. That 6.5% rate carries an illustrative APR of about 6.59% if the lender charges $3,000 in fees, and the APR is what a lock does not freeze on its own, since fees can still move. A quarter point of drift is not a rounding error.
Locking is a pricing decision, not an approval. Underwriting still has to say yes, and underwriting is the lender checking your income, credit, and the home before it will fund the loan.