Example 2.

Riley files a federal income tax return on a calendar year basis. On April 20, Riley began using 100 square feet of the home for a qualified business use. On August 5, Riley expanded the area of qualified business use to 350 square feet. Riley continued to use the 350 square feet until the end of the year. Riley’s average monthly allowable square footage is 150 square feet (100 square feet for May through July and 300 square feet for August through December divided by the number of months in the year ((100 + 100 +100 + 300 + 300 + 300 + 300 + 300)/12)).