5.12 Lump Sum Payments and Refinancing Mortgages

Learning Outcomes

Calculate the extra amount borrowed when refinancing a mortgage or the reduced payment size when renewing a mortgage and making a lump sum payment that drops the balance owing.

It is possible to borrow more money or pay off part of your mortgage when you go to renew your mortgage[1]. Let us first examine making a lump sum payment upon renewal (ie: making an additional payment when renewing your mortgage).

Lump Sum Payments

After a mortgage term is up and before a borrower renews their mortgage, they can choose to pay down some of the balance owing with a lump sum payment.  This is like the initial down payment but part-way through the mortgage.  It is often advisable to make these payments, if you can afford them, as they will save you a lot of interest if there are many years left in your mortgage.

Example 5.12.1

The Frasers term is up on their mortgage.  They owe $523,324.15 on their at the end of the term.  They have $125,000 saved up to pay down on their mortgage before they renew the mortgage.  They will renew for another 15 years.  They negotiate an interest rate of 2.88%, compounded semi-annually.  What is the size of their new monthly mortgage payments?

First, let us determine the amount they will borrow (PV):

[latex]\text{New PV} = $523,324.15 - $125,000 = $398,324.15[/latex]

Next, let’s input the all values into the BAII Plus and calculate the size of their payments (PMT):

B/E P/Y C/Y N I/Y PV PMT FV
END 12 2 15×12=180 2.88 +398,324,15 CPT −2,724.56 0

The Frasers will pay $2,724.56 per month on their mortgage.

 

Increasing the Size of a Mortgage Upon Renewal (Refinancing)

After a mortgage term is up, a borrower can choose to increase the size of their new mortgage[2] by borrowing additional money against the mortgage when they renew.  Unless necessary, it is often not advisable to increase the size a mortgage.  This is because a borrower will pay a lot of interest on the extra money borrowed if there are many years left on the mortgage.

Example 5.12.2

Craig and Joel’s mortgage term is up. For the last 5 years, their mortgage payments have been $3,904/month.  Interest rates have dropped since they first bought their place.  They are hoping to borrow some money to renovate their kitchen while still keeping their mortgage payments the same (at $3,904/month).  How much can they borrow to renovate if they owe $523,324.15 and have 15 years left on their mortgage?  Their new interest rate will be 1.99%, compounded semi-annually.

If we want to know how much Craig and Joel can borrow, we need to calculate the PV (amount owed) using the $3,904 payment and using the 15 years remaining to calculate N:

B/E P/Y C/Y N I/Y PV PMT FV
END 12 2 15×12=180 1.99 CPT +607,464.81 −3,904 0

Take the difference between the amount they can borrow (PV) and the original amount they would have owed to determine how much extra Craig and Joel can borrow:

[latex]\textrm{Extra Amount Borrowed} = \$607,464.81 – \$523,324.15 = \$84,140.66[/latex]

Conclusion: Craig and Joel can borrow $84,140.66 to renovate their kitchen[3].

Your Own Notes

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The Footnotes


  1. If you borrow more money when your mortgage term is up, this is called refinancing (instead of renewing).
  2. Up to 80% of the value of the house can be financed (borrowed).
  3. Provided that the new value of their mortgage does not exceed 80% of the assessed value of their house.  Their house would need to worth at least $759,331.02 for the bank to lend them up to $84,140.66 for their renovation.

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