Are you an employee or self- employed?  For self-employed, go to the General Info for the Business, and look for Other Situations- Subject to transportation service.  Later under expenses it will allow you to enter the per diem amount.

@syntzu

Self employed sole proprietor.  I figured it out though. As an owner operator truck driver, I didn't lose my per diem allowance/credit like company drivers did. But I couldn't figure out where to add it. Turns out it's added under the Meals section. I titled it "Federal Per Diem Allowance" and then put in my amount, which is calculated for 2019 as 80% of $66 per day. Thanks for replying. I was panicking a bit since, for me, it's a major deduction.

On an unrelated side note...I am curious, I know a Mary K who is a tax expert. She is best friends with my deceased brothers widow. His name was Michael, hers Saundra. What a small world if that is familiar to you. If so, hello and hi how are ya? If not, or if out of line, my apologies for the intrusion.

Thank you again.

Glad to help, and no I am not that Mary K but wouldn't that be neat!