How a Mortgage Rate Lock Works, and What Can Break It

A rate lock keeps your quoted mortgage rate from moving between the lender's offer and closing, as long as you close on time and your application does not change. Weeks can pass between the quote and closing day, and rates do not wait, so it helps to know exactly what a lock covers and what it does not.

1. What a rate lock is

The Consumer Financial Protection Bureau defines a lock-in or rate lock as an agreement that your interest rate will not change between the offer and closing, as long as you close within the specified time frame and there are no changes to your application. The CFPB notes that mortgage rates can change daily, sometimes hourly, and that if your rate is not locked, it can change at any time.

Rate locks are typically available for 30, 45, or 60 days, and sometimes longer.

2. What a lock is worth, in dollars

To see why a lock matters, assume a $350,000, 30-year fixed loan. The rates are illustrative, not quotes.

Over a full 30-year term, $115.08 a month adds up to more than $41,000. A half-point move during a busy closing period is not unusual, which is why buyers in a rising-rate market often lock as soon as they have an accepted offer and a loan they intend to use.

3. How to tell if your rate is locked

The CFPB says some lenders lock your rate as part of issuing a Loan Estimate, and some do not. Check the top of page 1 of your Loan Estimate to see whether your rate is locked and for how long. If it is not locked, the rate on the estimate can still change.

4. What can change a locked rate

A lock protects you from market movement, not from changes in your own file. According to the CFPB, a locked rate can still change if your application changes, including your loan amount, credit score, or verified income. Common reasons it lists:

• You change the kind of loan you are requesting or the amount of your down payment.
• The appraisal on the home comes in higher or lower than expected.
• Your credit score changes, for example because you applied for or took out a new loan, or missed a payment on an existing loan or credit card.
• Your lender could not document your overtime, bonus, or other income.

The practical lesson is to keep your finances steady between application and closing: no new credit, no missed payments, and quick responses to document requests.

5. The downsides

The CFPB names two. First, a lock may be expensive to extend if your transaction needs more time. Second, a lock may keep you from getting a lower rate if rates fall after you get your loan offer.

Delays happen for reasons outside your control, such as repairs, title issues, or appraisal scheduling. That is why the length of the lock matters. A 30-day lock might be enough for a straightforward purchase; a longer lock may be worth considering when the closing timeline is uncertain.

6. Questions to ask your lender

The CFPB notes that rate lock policies vary by lender. Before you lock, ask questions like these:

• How long is the lock, and is there a fee for it?
• What does it cost to extend the lock, and for how many days?
• If rates fall after the lock, is there any option to get the lower rate?
• When will written confirmation of the lock arrive, and will the Loan Estimate show it?
• What exactly would cause the locked rate to be repriced?

Get the answers in writing. A verbal "you're locked" is not the same as a documented lock with a date and time it expires.

7. Timing your lock

There is no perfect moment, and no one can reliably predict short-term rate moves. A sensible approach is to lock once you have a signed purchase contract, have chosen a lender, and have a realistic closing date, then choose a lock length that covers that date with some room to spare.

8. Key takeaways

• A rate lock keeps your rate from changing between the offer and closing if you close on time and your application does not change.
• Locks typically run 30, 45, or 60 days; page 1 of the Loan Estimate shows whether and how long your rate is locked.
• On a $350,000 loan, a half-point rise from 6.25% to 6.75% adds about $115 a month.
• Changes to your loan, appraisal, credit, or documented income can still change a locked rate.
• Extensions can be costly, so pick a lock length that covers a realistic closing date.