In 1989, the IRS updated its employee manual with information on how the agency will deal with a nuclear war.  According to the manual, the IRS will resume tax collection within 30 days of a nuclear attack.  Tax collection efforts will be focused on areas that produce the most taxes. The manual also states that the staff is to focus on collecting current taxes because the widespread destruction could make it nearly impossible to recover previously owed taxes.

Nuclear War? The IRS will be back to collect taxes in one month