May 8, 2006, Revised November 14, 2008
"Your web site contains 36 articles on adjustable rate mortgages (ARMs),
which account for about 25% of the market, and zero articles on
fixed-rate mortgages (FRMs), which account for the other 75%. Is this
not a little unbalanced?"
Ouch, you are right. My only excuse is that ARMs are more complicated
and borrowers need more help with them, but that does not justify a
score of 36 to nothing. This article is a small gesture of atonement.
What Is An FRM? Fixed Rate Versus Fixed Payment
An FRM is a mortgage that has no provision for changing the interest
rate. Hence, the rate stated in the note is fixed for the entire term of
the loan.
Usually, the term "FRM" also means that the payment is fixed for the
life of the loan and pays it off over the term. This should be (but
usually isn’t) called a "level-payment fully amortizing FRM" to
distinguish it from other types of loans that have a fixed rate but not
a fixed payment.
For example, one of the earliest types of fixed-rate mortgages was
repaid with equal monthly payments of principal, plus interest. If the
loan was for $300,000 at 6% and the term was 300 months, then the
payment in month 1 would be $1,000 of principal plus $1500 of interest
for a total $2500. Each month the total payment would decline because
interest would be calculated on a lower balance. This was the standard
type of mortgage in New Zealand for many years, despite the obvious
disadvantage of high payments in the early years.
A fixed-rate mortgage can also have a rising payment. The version in the
US is called a "graduated payment mortgage", or GPM. They appeared in
the early 80s and are still available from a few lenders. See
Graduated Payment Mortgages.
The interest-only version of a fixed-rate mortgage also does not have
fixed payments. Borrowers begin paying only the interest, which declines
if they voluntarily pay any principal, until the end of the
interest-only period. At that point, the payment jumps and it becomes a
level-payment fully amortizing FRM. See
Interest Only Mortgages.
By prevailing practice, the term "FRM" without any modifiers means a
mortgage with a fixed rate and level payments that fully pay off the
balance. For example, on a $300,000 30-year 6% FRM, the monthly payment
is $1798.66. If the borrower makes that payment every month for 30
years, the 360th payment will reduce the balance to zero.
Calculating the Fully Amortizing Payment
Where does that $1798.66 figure come from? It is calculated from an
algebraic formula, those interested can find it in
Formulas. The much easier way is use a
financial calculator, such as an HP19B, or an on-line calculator such as
my number 7a Monthly Payment Calculator: Fixed-Rate Mortgages.
Technophobes can buy a book of monthly payments at a book store.
Rising Principal Payments Over Time
On an FRM, the composition of the payment between principal and interest
changes every month. At the beginning, it is mostly interest but the
principal portion gradually rises over time. In the example, the
principal payment in month 1 is $299, in month 12 it is $316, and in
month 60 it is $401.
This feature, where borrowers make the same payment every month but the
saving component of the payment increases every month, is powerful but
underappreciated. Some borrowers don’t recognize that debt repayment is
saving, and many of those that do think they aren’t earning any return
on it. I am frequently asked whether they would not do better putting
their money in a bank account earning 3% than repaying their mortgage.
In fact, a principal payment of $100 on a 6% mortgage earns the same
return as a $100 bank deposit that pays 6%. The deposit earns $6 a year
in interest while the principal payment reduces interest payments by $6
a year. The effect on the borrower’s wealth is the same.
Of course, if you can earn 10% on your money, paying down a 6% mortgage
is not the best choice. The recent popularity of interest-only loans,
and option ARMs that allow borrowers to pay less than the interest, has
been encouraged by the notion that borrowers can earn a return higher
than the mortgage rate by investing their money elsewhere. In my view,
however, most borrowers cannot earn a return above the mortgage rate
without taking unacceptable risk.
Different Terms on FRMs
FRMs come with different terms, ranging generally from 10 years to 40
years, with the 15 and 30-year being the most popular. (In contrast,
ARMs are almost all 30 years.) This means that my articles on
Mortgage Term apply almost entirely to FRMs.