When you receive notification of your recognition of exemption. You can say your application for recognition of exemption is pending, but it would be a misrepresentation to say that you are now “tax-exempt.” If you filed within 27 months of the end of the month in which the organization was formed, and you receive your exempt status, it will be retroactive to the date of formation. But it would not be accurate to say you are exempt until you are exempt.