This bill proposes to amend Section 280E of the Internal Revenue Code of 1986, which currently disallows tax deductions and credits for businesses trafficking in controlled substances. Its core purpose is to explicitly ensure that businesses involved in trafficking marijuana cannot claim such deductions or credits. The amendment specifies that no deduction or credit will be allowed for expenditures by a trade or business if it consists of trafficking in marijuana or other controlled substances. This prohibition applies when such activities are illegal under Federal law or the law of any State where the business operates. These changes will take effect for amounts paid or incurred after the bill's enactment date.