First and foremost, I assume your debt ratio is NOT 999.99%, or anywhere much above 43%……. You’ve got plenty of time to explore other options, so that’s the good news. If you change lenders, any advance lock fee you’ve paid will be lost, but if the rate is low enough, it still might be to your advantage to look elsewhere. Another thing to consider is whether the builder/seller is paying any of your closing costs. Often they will only do so if you use their in house lender, so make sure you’re clear on that before pulling your loan. While 5% is not a great rate, it’s about right if you did a 180 day lock. The float down policy should be pretty defined, did you get a copy of it when you initiated the loan? Current “best execution” rates are more like 4.5 to 4.625%. If you can float down to 4.625%, you’re getting a good deal. If they hold you at 5%, I’d at least look at other options, and do so sooner rather than later so you have time to make a change if you decide that’s in your best interest.