For the following states, there is no tax-exempt status (usually because there is no corporate tax):
Nevada, New Hampshire, South Dakota (but do file for sales tax exemption), Washington, Wyoming.
For the following states, merely filing your nonprofit Articles of Incorporation gives you tax-exempt status:
Ohio, Rhode Island (but certain exempt organizations may have further filing requirements), Tennessee.
For the following states, you are automatically tax-exempt when you receive your IRS 501(c)(3) status:
Alaska, Colorado, Connecticut, Hawaii, Idaho, Illinois, Kansas, Louisiana, Michigan, Mississippi, Missouri, Nebraska, New Mexico, North Dakota, Oklahoma, Oregon, South Carolina, Virginia, West Virginia, Wisconsin.
For the following states, you are tax-exempt upon notifying the state that you have IRS 501(c)(3) status (requirements differ as to what must accompany the notification, whether just the IRS Determination Letter, Articles, Bylaws, etc.):
Alabama, Arizona, Arkansas, Delaware, Florida, Georgia, Indiana, Iowa, Kentucky, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New York, Texas, Utah, Vermont, Washington D.C.
For the following states, you must apply and qualify for separate state tax-exempt status, but it is not burdensome:
Montana, North Carolina, Pennsylvania.
For California: after you receive your 501c3, attach it to a filled-out Form 3500A and send it to the Franchise Tax Board.