Good point, Greta. covid-related provisions (CAA) apply to this, as well. Not allowing DOT to have 100% while everyone else does, would not make any sense.

https://www.perdiemplus.com/100-deduction-for-per-diem-in-covid-19-relief-package/

https://www.irs.gov/newsroom/irs-provides-guidance-on-per-diem-rates-and-the-temporary-100-percent-d...

"For a taxpayer properly applying the rules of Revenue Procedure 2019-48, Notice 2021-63 provides a special rule that allows the taxpayer to treat the full meal portion of a per diem rate or allowance as being attributable to food or beverages from a restaurant beginning January 1, 2021, through December 31, 2022."

https://www.overdriveonline.com/business/article/15282132/owneroperator-202122-per-diem-tax-breaks-j...

"Essentially, it allowed whatever share of an owner-ops' meals were eaten at a restaurant on any given day to be 100% deductible as a share of the per diem -- this year, set at $66 the first nine months of this year, $69 from October 1 forward. Those per diem rates, in a normal tax year, are deductible at 80%, or $52.80 and $55.20 respectively."