We made a good faith effort to file the initial "zero" return timely however we filed it in paper format not realizing a 990-PF is required to be filed electronically. The paper return was postmarked April 9 2022 and stamped as received by the IRS Apr 21 2022. I recently received the paperwork that the IRS returned to us postmarked 12-29-2022 because it needed to be filed electronically.