The short version
A rate lock is the lender's promise to hold your interest rate for a set number of days while your loan is processed. Common lock periods are 30, 45, and 60 days. Longer locks cost more, either in rate or in points.
My rule with purchase clients is simple: once you're in contract and you can live with the payment, lock it. The money you'd make guessing right on a quarter-point is small. The money you lose guessing wrong — and blowing a closing date — is not.
Refinances are different. There's no seller, no contingency clock, and no one waiting on you. That's the one place where floating a little longer is a defensible call.
What does a rate lock actually do?
When you lock, the lender commits to a specific rate and a specific pricing structure — the rate, the points, and the lender credits all get frozen together. That last part surprises people. You're not just locking a number on the note. You're locking the whole cost package attached to it.
A lock has an expiration date. If your loan doesn't fund by then, the lock is dead and you're back at whatever the market is doing that morning — or you pay to extend. That's why lock length and closing date have to be talked about at the same time, not two weeks apart.
One thing worth being clear about: locking doesn't guarantee your loan gets approved. It holds the price. If income, appraisal, or credit issues change the file materially, the terms can change with it.
- Locks are tied to a specific property address, loan amount, and program — swap houses and you start over
- Longer lock = higher cost, because the lender is carrying more risk for you
- Switching loan programs mid-stream (FHA to conventional, 30-year to 15-year) usually re-prices the lock
- A lock protects you from rates rising; it does not automatically hand you the benefit if they fall
How long should my lock be?
Match the lock to the real timeline, then add a cushion. If your purchase contract says 30 days and you're using a program with extra moving parts, a 30-day lock is cutting it close. I'd rather price a 45-day lock and close early than sprint toward a deadline and pay for an extension.
Here's where Sonoma County adds its own wrinkles. Fire-zone insurance can take longer to bind than buyers expect, especially outside city limits. Septic and well inspections on rural parcels in Healdsburg or west county add days. Condo projects need document review. Construction and renovation files have their own schedule entirely. None of that is exotic, but each one eats calendar.
I've seen this go sideways when a buyer picks the shortest lock because the rate looked a hair better, then spends the last week of escrow trying to get a carrier to write a policy on a property in a high-hazard zone. The extension fee wipes out the savings and then some.
What happens if my lock expires?
You extend, or you re-lock at current market. Extensions are priced in days and usually cost a fraction of a point — figures vary by lender and market conditions, so treat any number you read online as approximate and ask for your lender's actual extension schedule in writing.
Re-locking is where it stings. If rates moved up while your file sat, you eat the difference. If they moved down, most lenders apply worst-case pricing on a blown lock, which means you don't simply get the better rate. That policy exists to keep people from letting locks lapse on purpose.
Extensions also matter for the seller. In a deal where the closing date is contractual, an expired lock isn't just a pricing problem — it can turn into a performance problem. Sellers in this market have been willing to grant short extensions, but I've also watched one refuse and put the deposit in play. Don't let the lock be the reason you're asking.
What is a float-down, and is it worth it?
A float-down lets you capture a lower rate after you've already locked, usually once, and usually only if the market improves by more than a set threshold before your loan is docs-out. Some lenders offer it, some don't, and some charge for it up front.
The catch is almost always in the threshold. If the option requires an improvement of a quarter point or more in base pricing before it triggers, small moves do nothing for you. Ask three questions before you pay for one: how much does the market have to move, when is the deadline to exercise it, and what does the option itself cost?
My honest take — most borrowers overvalue the float-down and undervalue simply getting the file clean and closed. If rates drop meaningfully after you close, a refinance is available. A missed closing date is not undoable.
- Confirm the trigger threshold in writing, not verbally
- Ask whether the option costs anything if you never use it
- Find out the last day you can exercise it — it's usually before final docs, not before funding
- Compare the option's cost to what a future refinance would realistically run you
Should I lock before I'm in contract?
You can lock before you have an accepted offer with some lenders, on a to-be-determined property. It's a real tool, and in a rising-rate stretch it can be the right one. But it comes with strings: you're committing to a loan amount and program before you know what you're buying, and if the deal you eventually write looks different, the lock gets repriced anyway.
For most of my Santa Rosa and Petaluma buyers, the better sequence is to get fully underwritten first — not just pre-qualified. A pre-approval backed by underwriter review does two things: it makes your offer stronger in a multiple-offer situation, and it shortens the timeline after acceptance so you need less lock, which costs less.
If you're refinancing, there's no contract clock, so you have room to set a target. I tell refi clients to pick the number where the refinance makes sense for them — the payment, the break-even on costs, the term they actually want — and lock when it's hit instead of waiting for a bottom nobody can call.
Where a broker changes the math
Because we're a brokerage, we're not stuck with one lender's lock desk. Lock policies differ more than people realize — extension pricing, float-down availability, how long a lender will hold a construction or renovation file, whether they'll lock a to-be-determined property at all. On files with a longer runway, that difference is worth real money.
It also means that if a lender's turn times start slipping mid-transaction and your lock is at risk, we have options other than paying for an extension and hoping.
Call me at 707-595-5393 and tell me your closing date. The lock conversation should take about five minutes, and it should end with you knowing exactly what happens if the calendar slips.