There is no single number. The cap comes from points-and-fees compliance on your specific loan size, and you probably do not want the maximum anyway. Two things are going on: - Compliance. How many points a credit represents depends on your loan amount. A $20,000 credit is five points on a $400,000 loan, and lender compliance departments read the 'bona fide discount points' rules conservatively, so they often cap how much of a credit can be routed into a rate buydown. That is likely what your lender was flagging. - Diminishing returns. The further you buy below par, the less rate each additional point purchases. Five points of buydown rarely makes sense on the math alone. Our general guidance: put at most two to three points toward the rate, and send the rest of the credit to closing costs and prepaids (taxes, insurance, prepaid interest). You capture the useful part of the rate reduction and leave no big sunk cost behind if you refinance later. We lean against points when it is your own cash; negotiated seller money changes that math, since the alternative is often leaving the credit on the table. Confirm the specific cap with your lender, because it turns on your exact loan amount and their compliance read, but the strategy holds regardless of the number.