Below is a citation for an excellent article about the treatment of losses under section 199A, in the latest issue of the ABA’s Tax Lawyer:

72 Tax Law. 401
Tax Lawyer
Winter, 2019
Report
American Bar Association Section of Taxation
Copyright © 2019 by American Bar Association; American Bar Association Section of Taxation
COMMENTS CONCERNING THE TREATMENT OF LOSSES AND CERTAIN OTHER ISSUES REGARDING THE SECTION 199A DEDUCTION