Margin

Key Takeaways

• The margin is a fixed percentage written into the note at closing and it does not move for the life of the loan.
• Index plus margin equals the fully indexed rate, which is the rate the borrower pays once an adjustment takes effect.
• Washington defines the fully indexed rate by statute as the prevailing index rate plus the margin that applies after the introductory rate expires (RCW 19.144.010).
• Two loans following the same index can carry different rates, because the lender sets the margin and it is the piece a borrower can shop.

What It Means

The margin is the lender’s share of an adjustable rate. It is a fixed percentage written into the note at closing and, unlike the index, it never moves. Add the two together and the result is the fully indexed rate, the rate the borrower actually pays once an adjustment takes effect. Washington’s mortgage lending statute states that relationship outright, defining the fully indexed rate as the prevailing index rate plus the margin that applies after the introductory rate expires.

Because the margin is the piece the lender sets, it is the piece a borrower can negotiate. Two loans can follow the identical Index and still charge different rates, and across twenty-five remaining years a half-point difference in margin is real money. The margin is there to cover the lender’s cost of doing business, its risk, and its profit.

The margin also explains a payment shock that seems to come from nowhere. A loan opening at a discounted Teaser Rate can sit below its Fully Indexed Rate for years. When the discount expires the rate jumps to index plus margin, which can raise the payment sharply even if the index has not moved a single basis point.

How It Works in Washington

Washington writes the margin into statute rather than leaving it to the note alone. RCW 19.144.010 defines "fully indexed rate" as the index rate prevailing at the time a residential mortgage loan is made, plus the margin that will apply after the expiration of an introductory interest rate. That definition matters because RCW 19.144.020 then requires the disclosure summary of material terms, delivered within three business days of the application, to state whether the loan payments will adjust at the fully indexed rate.

The Mortgage Broker Practices Act reaches the same ground from the broker’s side. RCW 19.146.030 requires a written disclosure that, for a variable rate loan, gives the circumstances under which the rate may increase, any limitation on the increase, the effect of an increase, and an example of the payment terms resulting from an increase. A borrower shown only the discounted start rate on an Adjustable Rate Mortgage Arm has not been given what the statute asks for.

Washington also ties one loan feature to the first adjustment. RCW 19.144.040 permits a prepayment penalty only where it expires at least sixty days before the initial reset period of an adjustable rate mortgage, which is the moment index plus margin takes over from the introductory rate.

Example

Priya and Marcus each borrow $340,000 on a 30-year 5/1 adjustable rate mortgage, with the same introductory rate of 5.75 percent and the same index. Each starts at a principal and interest payment of $1,984.15. The only difference is the margin: Priya negotiated 2.50 percent and Marcus signed at 3.25 percent.

Five years later both loans reset with a balance of $315,391.44 and the index sitting at 4.00 percent. Priya’s fully indexed rate is 4.00 plus 2.50, or 6.50 percent, and her payment over the remaining 25 years becomes $2,129.55. Marcus’s is 4.00 plus 3.25, or 7.25 percent, and his payment becomes $2,279.67.

Same loan amount, same index, same start rate, same reset date. The 0.75 point difference in margin costs Marcus $150.12 more every month, about $45,036 across the remaining term.

Common Mistakes and Exam Traps

• The margin does not move. Every rate change on an adjustable loan traces back to the index, never to the margin.
• The margin is not the same as discount points. Points are paid once at closing, while the margin is a rate component charged for the life of the loan.
• A rate cap limits the result of index plus margin. It does not shrink the margin itself.
• Index plus margin gives the fully indexed rate, which can sit well above the introductory rate printed on the first payment coupon.