We are a small all-volunteer membership organization and and recently had a change to the position of treasurer. As soon as we discovered our error, we immediately prepared and filed the return before being notified by the IRS that it was late, thereby demonstrating that we acted responsibly and in good faith. We believe this demonstrates that we did not willfully neglect our filing requirement. To prevent future late filings we have placed the due date of the Form 990 on the calendar of the board of directors, and all new board members are educated on all the annual filing requirements that pertain to the organization.