The taxpayer, an on-call physician, worked 24-hour shifts three days a month from Friday–Sunday at a hospital 25 miles from his home. He drove to the hospital in a motor home that he used for rest and sleep when he was not needed in the hospital. For 2008 and 2009, he deducted 85% and 100%, respectively, of expenses related to the motor home because he used it as a “mobile office” 85% and 100%, respectively, of the time he was performing on-call duties. On audit, the IRS limited the deductions for motor home expenses to 19.42% and 22.23%, respectively, based on the ratio of business miles to total miles driven in each year. The Tax Court agreed with the IRS. Although the taxpayer used the motor home for business purposes when on call, he also used it personally, so expenses had to be allocated between business and personal use based on total mileage, not the time it was used as a “mobile office” while on-call. Jefferson Cartwright, TC Memo 2015-212 .