Wrong on both counts!
The refinance decision, if made rationally, has nothing to do with how long you have had your house and mortgage. What
matters is the interest rate on the old loan relative to the rate on the new loan, the balance on the old loan, the cost of
the new loan, and how long you expect to hold the new mortgage. How long you have already held it doesn’t matter.
Expectations about future tenure are important because a refinance trades off a lower interest rate, the benefit from which
grows over time, against the upfront costs of the refinance. The period over which the benefits just equal the costs is the
"break-even period." If you don’t hold the new loan that long, the refinance is a loser. You can find the break-even period on
any proposed refinance using calculators 3a, 3b, 3c and 3d.
The decision to make extra payments to principal, in contrast, is affected neither by how long you have been in the house
already, or how long you expect to hold it in the future. When you make extra payments to principal, you are reducing your
debt and increasing your equity in the house. You will realize this benefit when you sell, regardless of when this happens.
For example, let’s assume you pay an additional $100 in principal on May 1 and you sell the house on May 15. Then the
amount you net at the sale will be higher than it would have been had you not made the extra payment. The difference will be
$100 plus the interest on $100 for 15 days, which you would otherwise have had to pay.
