When Should You Lock Your Mortgage Rate?

A rate lock is your lender's guarantee that your interest rate will not change for a set window, even if the market moves against you, as long as you close in time. The right moment to lock is once you are under contract on a specific home and your loan is moving forward. Before you have a property and an accepted offer, there is usually nothing to lock.

How a lock works

When you lock, the lender holds your quoted rate for a fixed number of days. Common lock periods run 30, 45, or 60 days, timed to cover a normal closing. The clock starts the day you lock, so you want the window long enough to reach your closing date with a little cushion. Locking protects you from rate increases while your loan is in underwriting.

What happens if the lock expires

If your closing runs past the lock window, you will usually need a lock extension, and extensions cost money. That is why the length of the lock matters. A lock that is too short can force you into an extension fee or, worse, expose you to a higher rate right before closing. When we start your file, I set the lock period to match a realistic timeline for your loan type, since some loans take longer than others.

Can you still benefit if rates drop?

Sometimes. Some locks include a float-down option, which lets you capture a lower rate if the market improves meaningfully before you close. Not every loan or lender offers it, and there is often a cost or a limit on how far it can move. If you think rates may fall, ask about a float-down before you lock rather than after.

The short version

Lock once you are under contract. Pick a window that comfortably covers your closing. Ask about a float-down if you want a path to a lower rate. If you are still shopping and want to watch the market first, you can see today's rates or set a rate alert.