“Limitations are after 5 years from time of activity or discovery.”
Do you have a federal cite for that statement?
Title 18 section 3282 in general.
More specificly:
https://www.justice.gov/usam/criminal-resource-manual-650-length-limitations-period
I have since learned that the general provision may be overridden by specific laws. It is possible that the tax code has more specific statue of limitations.