The Mortgage Rate Lock, Explained Properly

What a rate lock actually commits both sides to

When a lender locks a loan, they are not setting aside a pot of money at a certain rate. They are taking a position in the secondary market to hedge the loan they expect to deliver. That is the mechanism behind everything else in this article, and understanding it makes the rest obvious.

Mortgage rates come from the price investors pay for mortgage-backed securities. When a lender commits to a rate today for a loan that funds in thirty days, they have promised something whose market value will change every day between now and then. They hedge that promise. The hedge costs money, and the longer the promise runs, the more it costs. That is why a 60-day lock prices worse than a 30-day lock on the same loan: you are buying a longer guarantee, and someone is paying for the risk.

The commitment runs both directions, though asymmetrically. The lender must honor the rate if the loan closes as described within the window. The borrower is expected to actually close that loan with that lender. If the borrower walks away to chase a better rate elsewhere, the lender is left holding a hedge against a loan that will never arrive, which is a real cost to them.

What a lock does not do is protect a file that changes. Locks are issued on a specific loan: a loan amount, a property, an occupancy type, a product, a term, a credit score band, and a lock period. Change any of those and pricing is recalculated. A borrower who locks and then drops their down payment, switches from primary residence to investment property, or has their credit score fall a tier has not lost the lock, but they have changed the loan the lock was priced on.

• A lock is a hedged commitment, not money set aside.
• Longer lock periods cost more because the hedge runs longer.
• The lender owes the rate; the borrower is expected to close the loan.
• The lock covers a specific file, not the borrower generally.
• Material changes to the file trigger repricing, even inside the window.

Lock periods and how they are priced

Standard lock periods usually run 15, 30, 45, and 60 days, with longer options available on new construction and some specialty products. The shortest lock that comfortably covers your timeline is almost always the right one, because every additional increment costs pricing.

The trap is picking a lock period based on optimism. A 30-day lock on a file that realistically needs 40 days is not a savings. It is a 30-day lock plus an extension fee, which usually costs more than a 45-day lock would have. Originators do this constantly because the shorter lock quotes better and the conversation is easier today.

Price the lock against the actual constraints of the file. When is the closing date on the contract? Is the appraisal ordered, and what are turn times in that market right now? Is the borrower self-employed with documents that will take two rounds? Is there a condo questionnaire in play, or an HOA that responds slowly? Every one of those adds days, and days are the only thing a lock measures.

For new construction, the rules change entirely. Extended locks running many months exist for exactly this scenario, often with an upfront fee and sometimes with a float-down provision attached. If your borrower's home will not be finished for six months, a 60-day lock is not a plan.

When to lock: the honest answer

Nobody knows where rates are going. Anyone who tells a borrower otherwise is guessing with someone else's money, and if they are wrong the borrower remembers who told them to float.

The defensible framework is not a prediction. It is a question about consequences. If rates rise a quarter point, does this borrower still qualify and still want this house? If the answer is no, lock. Their approval is sitting on a knife edge and the potential upside of floating is not worth the risk of losing the deal entirely.

If the answer is yes, and the borrower is genuinely comfortable with either outcome, floating is a legitimate choice. But it should be a decision the borrower makes with a clear understanding of what they are risking, not a decision the loan officer makes by default because nobody brought it up.

Practically, most purchase borrowers should lock once they are under contract and the file is real, because at that point they have a closing date, a deadline, and earnest money at risk. The exposure to a rate move is no longer theoretical.

Refinance borrowers have more room to float, because there is no seller waiting and no contract deadline. There is also less urgency, which cuts both ways, since refinance borrowers who float indefinitely waiting for a better number often watch the opportunity close entirely.

One discipline worth building: document the conversation. When a borrower chooses to float, send a short note confirming they chose to float, what that means, and that rates can move either direction. When rates rise the following week, that note is the difference between a difficult conversation and a formal complaint.

• Do not predict rates. Frame the decision around consequences.
• If a quarter-point rise breaks the approval, lock.
• Purchase borrowers generally lock once under contract.
• Refinance borrowers can float, but indefinite floating loses deals.
• Confirm float decisions in writing, every time.

Extensions, and what they actually cost

A lock extension is what happens when the loan does not close in the window. The lender extends the commitment for additional days, and the borrower generally pays for it, priced as a fraction of a point per day or in blocks of days.

Extensions are not catastrophic, but they are not free, and they are almost always avoidable. The overwhelming majority are caused by predictable delays: appraisal ordered late, conditions gathered slowly, a borrower who took nine days to send a bank statement, a title issue nobody chased.

Who pays is a real conversation. Many lenders allow the loan officer or branch to absorb an extension cost out of their own compensation, and many originators do exactly that when the delay was clearly their fault. That is a professional decision, not a rule. What is not acceptable is letting the borrower discover an extension fee on the Closing Disclosure without ever having been told it was coming.

The other path is a lock that expires entirely, which is worse. Depending on the lender's policy and how long ago it expired, the loan may be repriced at current market, and many lenders apply a worst-case pricing rule, meaning the borrower gets the worse of the original rate or today's rate. That rule exists to stop borrowers from letting locks lapse strategically when rates fall. It also means an expired lock in a rising market is genuinely expensive.

The management technique is simple and almost nobody does it: put the lock expiration date on your calendar the day you lock, with a reminder a week out. A week is enough time to fix most things. Two days is not.

• Extensions are priced per day or in day blocks, and usually paid by the borrower.
• Most extensions come from avoidable file-management delays.
• Originators sometimes absorb the cost when the delay was theirs.
• Never let an extension fee surprise a borrower at closing.
• Expired locks often trigger worst-case pricing, which is worse than extending.
• Calendar the expiration date the day you lock, with a one-week warning.

Float-downs and renegotiation when rates fall

The question every locked borrower eventually asks is what happens if rates drop. There are two possible answers and they are not the same thing.

A float-down is a feature purchased at the time of lock. It gives the borrower a contractual right, under defined conditions, to move to a lower rate if the market improves by more than a specified threshold before closing. It costs something up front, either in fee or in pricing, and it typically comes with rules: a minimum improvement required, a single exercise, and a deadline before closing. It is most common on extended locks for new construction, where the exposure window is long enough to justify the cost.

A renegotiation is not a right. It is a lender policy, applied case by case, that allows a locked loan to be repriced when the market has moved substantially in the borrower's favor. Lenders offer it because the alternative is the borrower walking to a competitor, which costs the lender more. Policies vary and typically require a meaningful move, not a small one, and often give back only a portion of the improvement.

How to handle this with a borrower is a matter of expectation setting. Do not promise a renegotiation, because you do not control the policy. Do explain, at lock, that locks protect against increases and that meaningful decreases are sometimes revisited but never guaranteed. Borrowers accept that framing readily when they hear it before the fact.

One caution about a tactic that comes up: a borrower who wants to abandon a locked loan and restart with a new lender to catch a lower rate. It sometimes works, and it costs time, potentially a second appraisal, and the risk of missing a contract deadline. It also burns a lender relationship. Walk through the full math and the calendar before anyone gets excited.

• A float-down is bought at lock and comes with defined rules and thresholds.
• A renegotiation is a lender courtesy, not a borrower right.
• Never promise a renegotiation you do not control.
• Set the expectation at lock: locks protect against rises, not the reverse.
• Restarting with a new lender has real costs and calendar risk.

The lock mistakes that show up over and over

Locking before the file is real. A lock on a borrower who has not been credit-approved, or on a property that has not been identified, is a lock on a guess. When the actual details arrive and they differ, the lock reprices and the borrower experiences it as a bait and switch.

Locking the wrong lock period out of optimism. Covered above, and worth repeating because it is the most common single error in the category.

Not telling the borrower what changes the price. Loan amount, occupancy, property type, credit score band, and product all affect pricing. A borrower who decides to put five percent less down after locking needs to hear the pricing consequence from you, before they commit to the change.

Quoting a rate without quoting the terms. A rate is meaningless without the lock period, the points, and the assumptions behind it. When a borrower compares your quote to a competitor's, they are usually comparing a 45-day quote with points to a 15-day quote without, and concluding you are expensive.

Going quiet near expiration. When a file is tight against the lock date, the instinct is to avoid the conversation until it is resolved. That is exactly backwards. A borrower told on day 25 that things are tight and here is the plan stays calm. A borrower told on day 30 that the lock expired does not.

Treating the lock as a paperwork step. The lock is where the loan officer's judgment is most visible to the borrower. Handle it well and they will refer you for years. Handle it poorly and they will remember the number they did not get.

• Do not lock a file that is not real yet.
• Pick the lock period from the file's constraints, not from the best quote.
• Explain up front what changes will reprice the loan.
• Always quote rate with lock period, points, and assumptions attached.
• Communicate early when a lock is tight, not after it expires.

Common questions