H.R.3424: To authorize appropriations for the purpose of establishing an office within the Internal Revenue Service to focus on violations of the internal revenue laws by persons who are under investigation for conduct relating to commercial sex acts, and to increase the criminal monetary penalty limitations for the underpayment or overpayment of tax due to fraud.

Authorizes appropriations to establish an office in the Internal Revenue Service (IRS) to investigate and prosecute violations of tax laws by individuals under investigation for criminal commercial sex activity.

Amends the Internal Revenue Code to increase criminal monetary and other penalties for attempts to evade or defeat tax, willful failure to file a tax return, supply information, or pay tax, aggravated failure to file tax returns, fraud and false statements, and underpayment or overpayment of tax due to fraud.