The first part of it was kind of common sense (at least to accounting types) - 3 years (statute of limitations for Federal returns), longer if your state has a longer SOL (like California). Then they threw a WTF item or two:
That last one is a doozy. Keep all your fraudulent stuff forever. SMH.4. Keep records for six years if income that should been reported was not reported, and it is more than 25 percent of the gross income shown on the return.
5. Keep records indefinitely if not filing a return.
6. Keep records indefinitely if filing a fraudulent return.