A mortgage rate lock is a promise with a clock on it: your lender agrees that your interest rate will not change between the offer and closing, as long as you close within a set time and nothing material changes in your application. Read carelessly, it feels like certainty. Read properly, it is a conditional promise, and the conditions, the expiry date, the points you are paying, and the changes that can re-price it, are exactly what the offer document is for. This guide teaches you to read that document line by line, so you sign a lock you understand rather than a rate you merely hope holds.
Mortgage Rate Lock: What the Confirmation Must State
Start with the document itself. You should receive a written rate lock confirmation, and your Loan Estimate, the standard form every lender must send within three business days of your application, should also state the lock position. At the top of page 1 of the Loan Estimate, it says whether your interest rate is locked, and if so, until when. If it says the rate is not locked, it can change at any time, and no verbal assurance overrides that.
A complete confirmation states five things. The locked interest rate itself. Any discount points or lender credits attached to that rate, explained below. The expiry date, and whether that date falls after your scheduled closing date, with room to spare. The loan terms the lock assumes: loan amount, loan type, down payment and property details. And what happens if closing slips, including extension costs and the process for relocking. If any of those five is missing or vague, ask for it in writing before you treat the rate as locked. The Consumer Financial Protection Bureau’s guidance on what a lock-in or rate lock is makes the same point in plain terms: a locked rate holds only if you close within the specified time frame and there are no changes to your application.
If your closing date is uncertain, say so, and price the longer lock rather than hoping for a cheap extension later.
Points, Credits and APR: Reading the Price of the Rate
Discount points are upfront payments that buy a lower rate. One point equals 1 percent of the loan amount, so one point on a $300,000 loan is $3,000. The amount of rate reduction one point buys is not fixed; it varies by lender and by market conditions, so a point at one lender is not the same bargain as a point at another. Lender credits work in the opposite direction: you accept a higher rate, and the lender credits some closing costs in return. Neither is inherently better. Points suit a borrower who will hold the loan long enough for the monthly saving to repay the upfront cost. Credits suit a borrower short on cash at closing, or one who expects to move or refinance before the higher rate costs more than the credit saved.
That trade-off is why the annual percentage rate, APR, matters alongside the interest rate. The interest rate is the cost of borrowing the principal. The APR is broader: it folds in certain upfront costs, including points and some fees, and expresses the total cost as a yearly rate. A loan with a lower interest rate but high points can therefore have a higher APR than a loan with a slightly higher rate and no points. When comparing lenders, compare the same things on the same basis: interest rate, APR, loan amount, term, points or credits, and total closing costs.
To see why the lock matters to the monthly payment, run the break-even maths on points the same way you would for any upfront cost: divide the points cost by the monthly saving, and the result is roughly how many months it takes to recover the payment. If you expect to move or refinance before that point, the points probably do not pay. Our guide on fixed vs adjustable mortgage rates explains the rate-type choice that sits underneath any lock decision, at the point where the kind of rate, rather than its lock, is the question. That post is scheduled for 30 October 2026, so it will be live before this article publishes.
What Can Break a Lock, and What Happens When the Clock Runs Out
A lock can change, or fall away, for reasons that have nothing to do with market rates. Common triggers are: changing the loan type or the down payment; a loan amount change; an appraisal that comes in higher or lower than expected; a credit score change, for example from a new application, a new loan or a missed payment during the process; and income the lender cannot document, such as overtime or bonus income that does not verify. None of these means the lender acted unfairly; they mean the loan the lock was priced for is no longer the loan being made. Keep the file steady after locking, and tell the lender immediately if anything material changes.
If closing slips past expiry, you typically face two options, neither free. You can extend the lock, paying a fee that varies by lender and by the length of extension, with illustrative ranges often quoted around an eighth to a quarter of a point for a week or two, and more for longer extensions, though actual fees vary and must be confirmed with your lender. Or you can let the lock lapse and relock at whatever rate the market offers that day, absorbing the full move if rates have risen. Compare those two costs in writing before the expiry date arrives, not after. A float-down option, where offered, is a third path: it lets you take a lower rate if market rates fall during the lock, usually for an upfront fee, and it is worth pricing only if the lock period is long or the market is volatile.
Shopping discipline helps twice over. First, request Loan Estimates from several lenders for the same loan type, amount and term, and compare them on the basis above. Second, do that shopping inside one tight window, since multiple mortgage inquiries in a short period are typically grouped for scoring purposes, as our guide on how credit inquiries affect your score explains at the point where application timing, rather than the lock itself, is the worry. That post is scheduled for 7 November 2026, so it will be live before this article publishes. And before locking at all, make sure preapproval and prequalification are not being confused: our guide on mortgage preapproval vs prequalification sets out what a lender actually checks at each stage, at the point where the strength of your application, rather than the rate, is the open question. That post is scheduled for 1 November 2026, so it will be live before this article publishes.
Frequently Asked Questions
Does a rate lock guarantee my loan will close?
No. A lock fixes the rate for a set period, subject to your application holding up. Final approval, appraisal, title and closing conditions still have to be met.
Where do I check whether my rate is locked?
At the top of page 1 of your Loan Estimate, and in your written rate lock confirmation. If the Loan Estimate says the rate is not locked, it can change at any time.
What is one discount point?
One percent of the loan amount, paid upfront to buy a lower rate. On a $300,000 loan, one point is $3,000. How much rate reduction it buys varies by lender.
What happens if my lock expires before closing?
You usually extend it for a fee or relock at current market rates. Compare both costs in writing before expiry, and check whether a float-down option was offered.
Can my locked rate still change?
Yes, if your application changes materially: loan amount, loan type, down payment, appraisal, credit score or documented income. Keep the file steady after locking and report changes immediately.
Disclaimer: This article is for general educational purposes only, not personalised financial, tax, or legal advice. Mortgage rates, lock terms, points, fees and lender policies vary and can change. Read your Loan Estimate and written rate lock confirmation, and confirm extension and relock terms with your lender, before acting.
