This involves a sole proprietor who years ago completed a direct-rollover of all Solo 401(k) Plan assets to an IRA.  They did not document a formal Plan Termination before the transfer.  The Plan Custodian closed the account.  Six months later (same calendar year) client partially returned assets to the Plan Custodian by direct-transfer back from the IRA.  The Custodian accepted the transfer into the previously closed account (same registration, same account number). The client resumed operating the Plan, even borrowing / repaying loans according to Plan Terms.  Not understanding the 100% distribution and account closing for 6 months by the Provider as a “final Plan year” event, (since the partial return rollover reinstated the original account) a final year Form 5500-EZ was also not filed (the Plan balance has always been < 250,ooo so, no 5500-EZ’s were ever filed).  Now years later, the client again direct-transfers the Plan’s entire account, this time intending to terminate the Plan.  However, reviewing prior year’s activity,  notes that the Custodian issued Form 1099-R reporting a “Total Distribution” for the earlier year’s activity described above.  On that year’s Form 1040 the transfer-out and back activity was reported non-taxable.  Dilemma,  if the earlier reported Total Distribution is regarded a final Plan Year  event, then a 5500-EZ  could be filed under the IRS’ Penalty Relief Program avoiding otherwise severe liability.  However, doing that and now submitting another 5500-EZ for the current termination of the same Plan raise’s question.  Also, was continuing the Plan by returning assets to the original account in less than 12 mons from a “deemed” termination a Successor Plan Rule violation?  Remember that  “formal” termination was never documented by the Plan or it’s Records Provider.  Would Voluntary Corrective Action Program filing be better to address/fix Plan operational issues (if any)?  Tax implications both for the Solo 401(k) and IRA?  Insights greatly appreciated.