Lock if your closing is within 30-45 days AND the live rate today meets your number, OR if you cannot stomach the downside risk of rates going higher before close. Float if your closing is 60+ days out, the market trend is in your favor, and you can absorb the downside if you guess wrong.

Within 30-45 days of closing. Locking earlier than that requires longer lock windows (60, 75, 90 days) that cost meaningful pricing - typically 0.125% to 0.5% in rate or rebate. Locking inside 15 days, where lenders price the shortest window, often gets the best price.

A float-down lets you lower your locked rate once before close if the market drops by a defined amount (often 0.25%). Lenders usually charge for this feature - either upfront (around 0.25 in rebate) or built into the rate. Worth it on a volatile market with a long lock.

Standard windows: 15, 30, 45, 60, 75, and 90 days. New construction or extended closes can lock up to 120-180 days for a meaningful pricing cost. The pricer above shows pricing across multiple lock periods so you can see the cost of each.

You are committed to the locked rate unless you bought a float-down option, switch lenders mid-process (which restarts disclosures and timing), or your lender voluntarily renegotiates (rare and usually only on big moves).

Indirectly - the guarantee triggers if another lender closes you at a strictly better combination of rate, fees, and MI on the same loan. If you locked too early and rates dropped a lot, you could close with a competing lender and the program would pay $2,000 on qualifying loans. The math has to make sense before you do this.