Q.If interest rates fall significantly after I've locked in, but before I close on a loan, can I renegotiate the rate?

A. Almost everything about a mortgage is endlessly negotiable. Just don't be surprised if a lower rate winds up costing you a few grand.

Start by asking whether you have a "float-down" lock that guarantees you won't pay more than the agreed-upon interest rate and allows you to take advantage of lower rates if they fall before closing.

Lenders usually charge a fee for this type of lock, but who knows, maybe you paid and didn't even know it.

If not, then ask your lender if it will lower the rate on your contract as a courtesy. Most won't. But you never know; your lender could be an exception to the rule.

Then ask whether you can buy down your rate by paying discount points. One point equals 1% of your loan amount. That might buy you a quarter-point off your interest rate.

It's usually a pricey way to lower your rate unless you plan to stay in the home for a long time. So make sure you know exactly how much you'll save on your monthly payments and how long it will take you to recoup that expense before making such an offer.