October 1, 1998, Revised November 27, 2006, November 16, 2007
Mortgage insurance is an alternative to a larger down payment, and also
to a second ("piggyback") mortgage for the amount of the loan above 80%
of property value. Knowing the cost of mortgage insurance is helpful in
deciding which of these options is least costly to the borrower.
"I have been advised not to borrow more than 80% of the value of my
property so that I won’t have to purchase mortgage insurance. The
insurance premiums I have been shown, however, only amount to about ¾ of
1% of the loan balance per year, which seems like small potatoes. Am I
wrong?"
Is a 4-ounce potato "small?" Anyone can weigh a potato, but judgments of
"small" and "large" are in the eyes of the eater. It is similar with
mortgage insurance.
Measuring the Cost of Mortgage Insurance: An Example
Since measuring the cost of mortgage insurance is more difficult than
weighing a potato, I’ll show you how to do it. But the measurement is
just step one. Step two is deciding what it means for you, which you
have to do for yourself. But to help in that, I am also going to show
you how to convert the mortgage insurance decision into an investment
decision, with which more people are familiar.
Lets take a concrete example. Assume I can obtain a 15-year fixed rate
mortgage at 7.5% and zero points to purchase a $100,000 house. Without
mortgage insurance, I could borrow up to $80,000 (80% of property
value), whereas with mortgage insurance I could borrow up to $95,000
(95% of property value). The insurance premium on the $95,000 loan is
.79% of the balance per year for the first 10 years, after which it
drops to .20%.
The best approach to measuring the cost of the insurance premium is to
view the loan of $95,000 as consisting of 2 loans: one for $80,000 which
has an interest cost of 7.5% consisting solely of the interest rate; and
one for $15,000 the cost of which includes both the interest rate and
the insurance premium. The interest cost on the $15,000 loan turns out
to be 12.7% if you stay in your house for up to 10 years, declining
slowly after that to 12% if you stay a full 15 years.
Since the insurance premium is only .79%, how can the cost of the
$15,000 loan be 5.2% higher than the cost of the $80,000 loan? The
reason is that while you are borrowing an additional $15,000, you pay
the premium on the entire $95,000.
Factors Affecting the Cost of Mortgage Insurance
The cost calculation above assumes that you take a fixed-rate mortgage
with a loan-to-value ratio of 95%, and pay mortgage insurance for 10
years. Change the assumptions and you change the cost. For example:
*On 85% and 90% loans, the cost is 13.4% and 12.5%, respectively. While
the insurance premiums are smaller, the incremental loans are also
smaller.
*On smaller loans within the same mortgage insurance premium bracket,
the cost is higher. For example, the cost of insurance on a 91%
fixed-rate loan, which has the same premium as a 95% loan, is 14.3%.
*Adjustable rate mortgages have higher insurance premiums, and therefore
higher costs, than fixed-rate mortgages.
Mortgage insurance costs can be reduced if you manage to get the
insurance removed early. For example, if the insurance on a 95%
fixed-rate mortgage is removed in 5 years but you stay with the mortgage
for 10, the cost falls to 10.8%. However, if you move in 5 years and pay
off the mortgage, there is no saving. On early termination of mortgage
insurance, see
Canceling Private
Mortgage Insurance (1) and
Canceling Private Mortgage Insurance (2).
A Rule of Thumb For Estimating Incremental Cost
Here is a handy rule-of-thumb for estimating the interest cost on the
incremental loan made possible by mortgage insurance, assuming the loan
runs 10 years. Divide the total loan by the incremental loan and
multiply the result by the annual insurance premium, e.g., 95,000
divided by 15,000 equals 6.33 which multiplied by .79% equals 5%. Adding
that to the interest rate gives an estimated cost of 12.5% on the
incremental $15,000 loan.
Viewing the Avoidance of Mortgage Insurance As an Investment Decision
Is an increase in interest cost of 5 percentage points on the
incremental loan "small potatoes"? The best way to answer this question
is to view the choice between the smaller loan without insurance and the
larger loan with insurance as an investment decision. Taking the smaller
loan means investing $15,000 in a larger down payment that provides a
risk free return of 12.5%. Is this an attractive investment?
Not if you don’t have the $15,000. Even if you have it, you would be
locking it up for an indefinite period, although you might borrow
against it using a home equity loan. Or you may not be impressed with a
12.5% return if you can earn more than that in your business, or are
paying more on credit card loans. On the other hand, if you have a bond
portfolio earning 7%, you might well want to liquidate it to invest in
the larger down payment. See
How
Much Should I Put Down?
In short, a 12.5% cost on an incremental loan made possible by mortgage
insurance is like a 4-ounce potato. It will be "small" to some and
"large" to others.
Piggyback Loans As An Alternative to Mortgage Insurance
The cost of mortgage insurance can also be compared to the cost of a
second mortgage for the loan amount that exceeds 80% of property value.
See Piggyback Loans: Two Mortgages Cost Less Than One?. This article
describes my calculator 13a,
Two Mortgages Versus One Larger Mortgage, which pulls together all
factors affecting the costs of PMI versus a second mortgage.