Client receives letter for typical 5500 Audit for 2015 Plan Year (calendar year). Form filed was Form 5500-EZ for Owner & Spouse. During audit it was discovered that data submitted by Client does not tie into W-2 of Spouse. Looking back it is determined of the years back to plan inception (2007), only 2 years tie into the Spouse's actual W-2 for that year. During the other years the Spouse's income was slightly overstated by $1,400. Result is that monies allocated in those years exceed maximum deductible contribution.
Question: Is related penalty tax only applicable for 3 years back, and does that mean 2015, 2014, 2013 and 2012?