Final answer:
If a taxpayer does not follow a revenue ruling and the IRS audits their return, there can be several consequences including disallowed deductions or credits, penalties and interest on underpaid taxes, and potential criminal charges for tax evasion.
Step-by-step explanation:
If a taxpayer does not follow a revenue ruling and the IRS audits their return, there can be several consequences. The IRS may disallow certain deductions or credits claimed on the return, resulting in an increase in the taxpayer's tax liability. Additionally, the taxpayer may be subject to penalties and interest on any underpaid taxes. Finally, if the IRS determines that the taxpayer intentionally disregarded the revenue ruling, the taxpayer may face criminal charges for tax evasion.