It would seem to me that your IRA basis for NJ purposes includes any NJ-taxed amount you put into a 401k or similar via payroll deduction while residing in NJ and rolled over.
Do you know exactly what that amount is? probably not.
I never did convert any of my 401k to an IRA.
Therefore, I know exactly how much I put into the IRA because I have all my 5498 records.
As you may or may not know, NJ recovery worksheet is relatively new (2013). At this time, NJ recovery only considers IRAs.
I haven't really researched it any more than that.
There may be other nuances.
