Here we can take an example of change in expected useful life.

X LTD has machine costing $50,000, its expected useful life of 5 years and no residual value is expected at the end of the machine’s useful life.

After 3 years , the remaining useful life of the machine was estimated to be only 1 years.

X LTD should calculate for the change in estimate prospectively by allocating the net carrying amount of the asset over its remaining useful life. No adjustment is required to restate the depreciation charge in previous accounting periods.

Depreciation expense will be as follows-

Expected useful life of the machine has reduced at the end of third year, so the depreciation expense is increased accordingly in years 3 and 4 by $5,000.

Now we can give the following answers in summarised form-

1.  How many years of depreciation have already been recorded?

Answer- Here change has been taken after third year so depreciation expense recorded in previous 2 years would not affected.

2.  What is the revision in useful life or salvage value?

Answer-The revision in useful life is that, after 3 years , the remaining useful life of the machine was estimated to be only 1 years instead of 2 years.

3.  What was depreciation expense per year BEFORE AND AFTER the revision?

Answer- For this purpose we can go through the table mentioned above.