Ref: Notice 2019-55
Many businesses use the meals and incidentals (M&IE) rate to substantiate out-of-town expenses without specific receipt reimbursement. The new rate is $66 per day in the US and $71 per day outside the US.
To use the per diem method, the business needs to establish that the person (owner or employee) was traveling away from home on business through a calendar or other documentation (e.g., airline tickets).
Under current federal tax law, employees are not allowed a deduction for non-reimbursed employee expenses. Therefore, the above would apply at the business level and the employee should seek reimbursement from the employer under either the per diem or actual receipt methods.