[masraum]

Originally Posted by 911boost

Holy crap!

I would never be able to sleep. I am about as square as it comes to paying taxes. I use an Accountant and have never taken a short cut, or tired to cheat on them at all. There were years I could have bought a nice Honda Accord for the checks I was sending in.

This year I get a decent amount back.

Hopefully your friend doesnt get busted.

Seems it's more a "when" than an "if", but I suppose it's possible that folks could slip through the cracks.

I wonder if there's any sort of timeline after which the IRS snoozed and lost. I assume there is not.

According to the American Bar Association, the IRS will usually audit the "last 3 years" but in certain circumstances can go back an additional 3 years (6 total).
https://www.americanbar.org/groups/business_law/resources/business-law-today/2017-august/irs-can-audit-for-three-years/
But

No Return or Fraudulent Return.
What if you never file a return or file a fraudulent one? The IRS has no time limit if you never file a return or if it can prove civil or criminal fraud. If you file a return, can the IRS ever claim that your return didn’t count so that the statute of limitations never starts to run? The answer is “yes.” If you don’t sign your return, the IRS does not consider it a valid tax return. That means the three years can never start to run.