Statute is later of filing due date or when you filed looking back 3 years.
How much depletion was missed over those 7 years and what was your marginal federal and state tax rate? If material, CPA is on the hook for that. His or her E&O insurance will pick up the cost plus interest.
Everyone makes mistakes. I made a ton. If I cost taxpayer tax that would not have otherwise been owed, I ponied up But not taking statutory depletion on oil and gas is negligent and imho should be reimbursed to you via cash or credited fees (which I wouldn’t recommend the latter cause u need a better cpa. This stuff ain’t rocket science).
Btw if you have caliche sales you get 5% statutory.
That’s what I think.
T (HAPPILY retired CPA of 34 years effective August 1, 2021).