When a bond is sold at a discount, the amount of the bond discount must be amortized to interest expense over the life of the bond. Since the debit amount in the account Discount on Bonds Payable will be moved to the account Interest Expense, the amortization will cause each period’s interest expense to be greater than the amount of interest paid during each of the years that the bond is outstanding.
The preferred method for amortizing the bond discount is the effective interest rate method or the effective interest method. Under the effective interest rate method the amount of interest expense in a given accounting period will correlate with the amount of a bond’s book value at the beginning of the accounting period. This means that as a bond’s book value increases, the amount of interest expense will increase.
Before we demonstrate the effective interest rate method for a 5-year 9% $100,000 bond issued in a 10% market for $96,149, let's highlight a few points:
The following table illustrates the effective interest rate method of amortizing the $3,851 discount on bonds payable:
A |
B |
C |
D |
E |
F |
G |
|---|---|---|---|---|---|---|
Date |
Interest Payment Stated 4.5% x Face |
Interest Expense Mkt 5% x Previous BV in G |
Amortization of Bond Discount C minus B |
Balance In the Account Bond Discount |
Balance In the Account Bonds Payable |
Book Value of the Bonds F minus E |
Credit Cash |
Debit Interest Expense |
Credit Bond Discount |
||||
Jan 1, 2009 |
$ 3,851 |
$ 100,000 |
$ 96,149 |
|||
Jun 30, 2009 |
$ 4,500 |
$ 4,807 |
$ 307 |
$ 3,544 |
$ 100,000 |
$ 96,456 |
Dec 31, 2009 |
$ 4,500 |
$ 4,822 |
$ 322 |
$ 3,222 |
$ 100,000 |
$ 96,778 |
Jun 30, 2010 |
$ 4,500 |
$ 4,839 |
$ 339 |
$ 2,883 |
$ 100,000 |
$ 97,117 |
Dec 31, 2010 |
$ 4,500 |
$ 4,856 |
$ 356 |
$ 2,527 |
$ 100,000 |
$ 97,473 |
Jun 30, 2011 |
$ 4,500 |
$ 4,874 |
$ 374 |
$ 2,153 |
$ 100,000 |
$ 97,847 |
Dec 31, 2011 |
$ 4,500 |
$ 4,892 |
$ 392 |
$ 1,761 |
$ 100,000 |
$ 98,239 |
Jun 30, 2012 |
$ 4,500 |
$ 4,912 |
$ 412 |
$ 1,349 |
$ 100,000 |
$ 98,651 |
Dec 31, 2012 |
$ 4,500 |
$ 4,933 |
$ 433 |
$ 916 |
$ 100,000 |
$ 99,084 |
Jun 30, 2013 |
$ 4,500 |
$ 4,954 |
$ 454 |
$ 462 |
$ 100,000 |
$ 99,538 |
Dec 31, 2013 |
$ 4,500 |
$ 4,962 |
$ 462 |
$ 0 |
$ 100,000 |
$ 100,000 |
Totals |
$ 45,000 |
$ 48,851 |
$ 3,851 |
|||
Let’s make a few points about the above table:
If the company issues only annual financial statements and its accounting year ends on December 31, the amortization of the bond discount can be recorded on the interest payment dates by using the amounts from the schedule above. In our example, there is no accrued interest at the issue date of the bonds and at the end of each accounting year because the bonds pay interest on June 30 and December 31. The entries for 2009, including the entry to record the bond issuance, are shown next.
Jan 1, 2009 Cash 96,149
Discount on Bonds Payable 3,851
Bonds Payable 100,000
Jun 30, 2009 Interest Expense 4,807
Discount on Bonds Payable 307
Cash 4,500
Dec 31, 2009 Interest Expense 4,822
Discount on Bonds Payable 322
Cash 4,500
The journal entries for the year 2010 are:
Jun 30, 2010 Interest Expense 4,839
Discount on Bonds Payable 339
Cash 4,500
Dec 31, 2010 Interest Expense 4,856
Discount on Bonds Payable 356
Cash 4,500
The journal entries for the years 2011 through 2013 will also be taken from the schedule shown above.
Comparison of Amortization Methods
Below is a comparison of the amount of interest expense reported
under the effective interest rate method and the straight-line method.
Note that under the effective interest rate method the interest
expense for each year is increasing as the book value of the bond
increases. Under the straight-line method the interest expense
remains at a constant amount even though the book value of the bond
is increasing. The accounting profession prefers the effective interest
rate method, but allows the straight-line method when the amount of bond
discount is not significant.
Effective Interest Rate Method |
Straight-Line Method |
|||
|---|---|---|---|---|
Year |
Interest Expense |
Book Value at Beg. of Year |
Interest Expense |
Book Value at Beg. of Year |
2009 |
$ 9,629 |
$ 96,149 |
$ 9,770 |
$ 96,149 |
2010 |
$ 9,695 |
$ 96,778 |
$ 9,770 |
$ 96,919 |
2011 |
$ 9,766 |
$ 97,473 |
$ 9,770 |
$ 97,689 |
2012 |
$ 9,845 |
$ 98,239 |
$ 9,770 |
$ 98,459 |
2013 |
$ 9,916 |
$ 99,084 |
$ 9,771 |
$ 99,229 |
Totals |
$ 48,851 |
$ 48,851 |
||
Notice that under both methods of amortization, the book value at the time the bonds were issued ($96,149) moves toward the bond’s maturity value of $100,000. The reason is that the bond discount of $3,851 is being reduced to $0 as the bond discount is amortized to interest expense.
Also notice that under both methods the total interest expense over the life of the bonds is $48,851 ($45,000 of interest payments plus the $3,851 of bond discount.)
Summary of the Effect of Market Interest Rates on a Bond’s Issue Price
The following table summarizes the effect of the change in the market interest rate on an
existing $100,000 bond with a stated interest rate of 9% and maturing in 5 years.
Bond’s Stated Interest Rate per Year |
Market Interest Rate per Year |
Issue Price of Bond (Present Value) |
Bond Issued At |
|---|---|---|---|
9% |
9% |
$100,000 |
Par |
9% |
8% |
$104,100 |
Premium |
9% |
10% |
$ 96,149 |
Discount |
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