How long does a 501c3 last?

Great question I field on such a regular basis!

Under the new regulations, a new 501(c)(3) organization will be classified as a publicly supported charity, and not a private foundation, if it can show that it reasonably can be expected to be publicly supported when it applies for tax-exempt status.  English translation:  Make sure that at leas one-third of your contirbutions come from public sources (and not your personal checking account), and you will likely pass the test.

Under the old regulations, an organization that wanted to be recognized by the IRS as a publicly supported charity instead of a private foundation had to go through an extended two-step process. First, the organization had to declare that it expected to be publicly supported on an on-going basis. Then, after five years, it had to file Form 8734, Support Schedule for Advance Ruling Period, showing the IRS that it actually met the public support test. If it didn’t meet the test, it was designated a tax-exempt private foundation and would be subject to stricter rules.

The new rules no longer require the organization to file Form 8734 after completing its first five tax years. Moreover, the organization retains its public charity status for its first five years regardless of the public support actually received during that time. Instead, beginning with the organization’s sixth taxable year, it must establish that it meets the public support test by showing that it is publicly supported on its Schedule A to Form 990, Return of Organization Exempt From Income Tax.

Hope that settles the question!