IRS clarifies per-diem rules after TCJA changes.

The IRS on Nov. 26 updated the rules for using per-diem rates to substantiate the amount of ordinary and necessary business expenses paid or incurred while traveling away from home, in light of changes enacted by the law known as the Tax Cuts and Jobs Act (TCJA), P.L. 115-97 (Rev. Proc. 2019-48). The revenue procedure supersedes and modifies the rules that applied to the per-diem method under Rev. Proc. 2011-47. Taxpayers are not required to use the method described in the revenue procedure and may instead substantiate actual allowable expenses, provided they maintain adequate records to support the deductions.

The new revenue procedure does not contain the per-diem rates for the current fiscal year. Those were published in Notice 2019-55, which contains the rates that are in effect from Oct. 1, 2019, to Sept. 30, 2020, and are explained at tinyurl.com/qmaksxc.

The TCJA suspended the miscellaneous itemized deduction that employees could take for nonreimbursed business expenses, but self-employed individuals and certain employees, such as armed forces reservists, fee-basis state or local government officials, eligible...