Your company owns any points earned from charges made on their corporate card, but you own the frequent flier miles you're logging. If it's your name on the plane ticket and your butt in the seat, those are your miles. It's up to you to claim them, of course.

Legally, frequent flyer miles are almost always considered the property of the individual traveler (the employee), even if the company paid for the ticket. This is because airline loyalty programs are contracts between the airline and the specific person flying, and miles are non-transferable assets. Most companies allow employees to keep these miles as a "perk" for the inconvenience of business travel. However, a company can implement a formal policy in their employee handbook stating that miles earned on business trips must be used for future business travel. While rare due to the logistical difficulty of tracking and redeeming them, such policies are legally enforceable if agreed upon in a contract. From a tax perspective in the U.S. and UK, the IRS and HMRC generally do not treat these miles as taxable income as long as they were earned through standard commercial travel programs available to the general public, providing a significant tax-free benefit for frequent business travelers.