The first regime: a price, disclosed on a line of its own. A discount point is a payment for a lower rate, and Regulation Z gives it a working definition when it needs one. A bona fide discount point is "an amount equal to 1 percent of the loan amount paid by the consumer that reduces the interest rate … based on a calculation that is consistent with established industry practices for determining the amount of reduction in the interest rate … appropriate for the amount of discount points paid" (12 CFR 1026.32(b)(3)(i)). Two things follow. The size of a point is fixed by arithmetic, so it is comparable across lenders. How much rate a point buys is not fixed by anything: it is the lender's own pricing decision, it moves with the market, and it differs between lenders on the same day. Any figure quoted as the standard rate reduction per point is describing one lender's sheet on one morning.
The second regime: a threshold, not a price. "Points and fees" at 12 CFR 1026.32(b)(1) is a defined aggregate that sweeps in finance charges, loan-originator compensation and certain third-party and real-estate-related charges. Its job is to test whether a mortgage crosses into high-cost status under 1026.32(a)(1)(ii), and it does the same work in the qualified-mortgage rules. A borrower who reads "points and fees" as "the points I paid plus my fees" has misread it, and the consequences of the test belong to the predatory lending entry.
The two senses meet at one provision, and it is the sharpest thing in this area. Regulation Z excludes from "points and fees" up to two bona fide discount points if the interest rate without any discount does not exceed the average prime offer rate by more than one percentage point; and if none were excluded on that basis, up to one bona fide discount point if the undiscounted rate does not exceed that benchmark by more than two percentage points (12 CFR 1026.32(b)(1)(i)(E) and (F)). The logic is that buying down a rate that was already competitive is a genuine purchase, while buying down a rate that was far above the market looks more like a fee dressed as a discount. The exclusion narrows precisely as the starting rate gets worse.
The third regime: prepaid interest, and the tax rule runs opposite to the folklore. Points are interest for federal income tax purposes, and IRS Publication 936 states the default plainly: "you generally can't deduct the full amount of points in the year paid. Because they are prepaid interest, you generally deduct them ratably over the life (term) of the mortgage." Full deduction in the year paid is the exception, and it requires meeting nine conditions together. The loan must be secured by your main home; paying points must be an established business practice in the area; the points paid must not exceed what is generally charged there; you must use the cash method; the points must not have been paid in place of amounts ordinarily stated separately, such as appraisal, inspection, title and attorney fees and property taxes; the funds you provided at or before closing, plus any points the seller paid, must be at least as much as the points charged; the loan must be used to buy or build your main home; the points must be figured as a percentage of the principal; and the amount must be clearly shown as points on the settlement statement. A loan to substantially improve your main home needs only the first six.
Three consequences of that list catch people out. A second home never qualifies: Publication 936 states that points on a loan secured by a second home may be deducted only over the life of the loan. An ordinary refinance does not qualify either, though where part of the refinanced proceeds substantially improves the main home, the part of the points allocable to that improvement can be deducted in the year paid. And on a home equity, line of credit or credit card loan whose proceeds are not used to buy, build or substantially improve the home, the points "are not deductible" at all.
Two smaller rules worth carrying. The funds you provided for the sixth test "aren't required to have been applied to the points" and "can include a down payment, an escrow deposit, earnest money, and other funds you paid at or before closing for any purpose", so a deposit committed months earlier can be what makes the deduction available. And where points are being deducted ratably and the mortgage ends early, through prepayment, refinancing or sale, the remaining balance is deductible in the year it ends, with one exception: refinancing with the same lender pushes the remaining balance onto the new loan's term instead.
One dated reference to read around. Publication 936's ninth test refers to the amount being shown on "the settlement statement (such as the Settlement Statement, Form HUD-1)". For most consumer mortgages that form was replaced in 2015 by the Closing Disclosure prescribed at 12 CFR 1026.38. The requirement is that the charge be clearly shown as points on the settlement statement the transaction actually produced.