I locked in February on a 180-day lock: 3.25%. There were some documentation issues that I had to rely on a third-party (the IRS) to resolve, so I had to start looking elsewhere. Rocket Mortgage was able to lock me at 5.25% (around April/May) - this would cost me an additional $400 each month. (Fortunately the original lender was able to make to adjust what they were asking for - it wasn't a matter of not closing the loan, but it meant they had to hold it rather than selling it while the IRS gets their act together)