State returns still due on April 15: Delaware, Hawaii, Mississippi, and New Hampshire. State returns due on May 17: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, DC, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Maine, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Utah, Vermont, Virginia, West Virginia, and Wisconsin. State returns due later than May 17: Iowa (June 1, 2021), Louisiana, Texas, Maryland, and Oklahoma (June 15, 2021).