what happens when you pay off your principle balance without a payoff?
The lender pay-off is a figure that helps the debtor understand the exact balance owed up to a certain date into the future, including misc. charges (for reconveyance, recording processing, etc.) Technically, you don't need a "demand" or lender pay-off, unless you are refinancing a loan. Usually the new lender wants evidence of the amount owed vs. the loan you are applying for. But if you just won the lotto and want to pay-off the mortgage you simply need to pay enough to cover the entire debt plus those misc. charges. Don't rely on your last mortgage statement, it's not the pay-off amount. If you pay short, they won't release the lien. If you over-pay, you'll get a refund. Good luck!
There's no logical reason to make a full payment without first obtaining a written payoff from your servicer. Since interest on mortgages is charged in arrears, and applies until the loan is paid in full, you cannot obtain an accurate payoff balance without ordering a payoff. If you did overpay, you would eventually get the excess funds back, but when payoffs can be ordered via phone or website, do yourself a favor and order one once you know the date you expect your servicer to receive your final payoff.
Mortgage payoffs are extremely easy to get from your mortgage company. If you can access your mortgage information online, there is often an option right there on that page where you can request a mortgage payoff. It is a free service provided by your lender. Without it you will really never "payoff" your mortgage even $10 owed on the mortgage will cause you problems down the road.