Between the day you are quoted and the day you close, the market keeps moving. A mortgage rate lock holds your quoted rate still across that gap. This guide is educational only and covers what a lock commits both sides to, lock periods and their cost, float-downs, and what happens when a lock runs out.
What a rate lock does
A lock fixes the interest rate and the associated pricing — points and lender credits — on a specific loan scenario for a defined number of days. It is tied to that scenario, not to you personally, so changing the inputs can reprice it:
- A different loan amount, product, or term
- A materially different credit profile at final underwriting
A lock is a two-way commitment. If rates fall afterwards, you are generally held to the locked rate unless you bought a float-down or the company offers a renegotiation policy.
Locking requires a specific property and an application in process — one difference between a preapproval and a locked loan. See what a mortgage preapproval actually checks.
Common lock periods and costs
Lock periods are quoted in days — 15, 30, 45, and 60 are typical, with longer windows for new construction.
The pricing logic is consistent: longer locks cost more. Holding a rate open is risk for the company, and it shows up as slightly worse pricing rather than a separate fee. A short lock you cannot close within is a false economy — extending later costs more than buying the right window at the start.
Float-down options explained
A float-down lets you take a lower rate if the market improves after you lock. Terms vary widely:
- It usually requires the market to improve by a minimum threshold before it triggers
- It is often exercisable once, within a defined window before closing, and is not offered on every product
Whether it is worth it depends on volatility and how much of the improvement the threshold consumes. For what drives those moves, see how current mortgage interest rates are set.
Extensions and expired locks
Delays are common — appraisal scheduling, title issues, document conditions, a seller pushing the date.
- An extension buys additional days, usually priced as a fraction of a point per day or per block.
- If a lock expires, the loan generally returns to current market pricing, and some companies apply a worst-case rule where you receive the worse of the original or current rate.
Ask before you lock: what an extension costs per day, and what happens if the lock expires. Get it in writing.
Timing a lock around your closing
There is no reliable way to time the market, so treat locking as risk management, not speculation:
- Choose a period covering your realistic closing date plus a buffer, not the optimistic one
- Float only if you have genuine flexibility on the closing date
- Confirm points and credits are locked alongside the rate; a guide to home loan options and how rates work covers the product side
Compare the locked rate and its pricing on a Loan Estimate, not by phone, so the terms are documented.
Compare advertised offers
Lock periods, float-down terms, and extension pricing vary by company. Browse finance companies and compare advertised offers, then confirm the lock policy in writing before you commit.
Frequently asked questions
When should you lock in a mortgage rate?
Most borrowers lock once they are under contract with a realistic closing date, choosing a lock period that covers it with a buffer. Locking earlier reduces uncertainty; floating only helps if you have real flexibility on timing and could absorb a higher payment.
What happens if my rate lock expires before closing?
The loan usually returns to current market pricing, and some companies apply the worse of your original or the current rate. Extensions are typically available for a fee charged per day or in blocks. Ask about both costs before you lock.
Can I get a lower rate if the market drops after I lock?
Only if your agreement includes a float-down option or the company offers a renegotiation policy. Float-downs generally cost something, require the market to improve by a set threshold, and can usually be used once within a defined window before closing.
Disclaimer: GoFunding.Shop is an advertising marketplace, not a lender, bank, broker, credit-repair company, or financial advisor. We do not approve applications, set rates, or guarantee funding. Always confirm the full terms — APR, fees, and repayment schedule — directly with the advertising company before you apply.