Once you are under contract, the conversation turns to locking your rate. Locking is one of the few moments in the mortgage process where timing genuinely matters, so it is worth understanding what you are agreeing to. Everything below is illustrative; rates and products are subject to change, and a lock is not itself a commitment to lend.
What a lock actually guarantees
A rate lock is the lender's commitment to honor a specific interest rate and pricing for a defined period, regardless of what the market does in the meantime. If rates rise during your lock, you are protected. If rates fall, you are generally still held to the locked rate unless your lock includes a float-down (more on that below).
The lock is tied to a particular loan amount, program, and property. Change the loan materially and the lock terms can change with it.
Lock periods and their cost
Locks come in lengths — commonly 30, 45, or 60 days, sometimes longer. The longer the lock, the more the lender is exposed to market movement, so longer locks generally carry slightly higher pricing. The practical rule: lock for long enough to comfortably reach closing, but not so long that you pay for time you do not need.
If your closing slips past the lock expiration, most lenders offer an extension for a fee. Extensions are routine, but they cost money, which is why a realistic closing timeline matters when you choose a lock length.
Float-downs
A float-down is an option that lets you capture a lower rate if the market improves meaningfully after you lock, while keeping your protection if rates rise. It is a one-directional safety valve. Float-downs usually come with conditions — a minimum improvement threshold, a cost, or a one-time-use limit — so they are a tool for specific situations, not a free upgrade.
When to lock
There is no way to reliably time the bottom; anyone who claims otherwise is guessing. The sensible approach is to lock once you are confident in your closing timeline and comfortable with the pricing in front of you, rather than chasing a market you cannot control.
The Alliance take
We walk every client through their lock decision in plain terms — what the period costs, when the clock starts, and whether a float-down is worth it for their situation. The point is an informed decision, not a gamble.
Under contract and weighing when to lock? Start your application or reach out and we will lay out the tradeoffs for your specific timeline.