Happens ALL the time; you have 5500s required until there are zero assets. For example, terminate a plan effective 12/31/18 (we never terminate 12/1, but you might have some unknown reason for doing so). File with IRS for approval, maybe 4/1/19. Wait for IRS approval which come 2/1/20. Start distributions in 2020. Hope that they all will be out by 12/31/20. File 5500s for 2018, 2019, 2020 if all money is out by then. No big deal.