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Bylaws are not required, however, (only) IF adopted they must be filed with the IRS as follows:
Although bylaws, the governing rules of an organization, are highly recommended for 501(c)(3) non-profit organizations, they are not required. If, however, they are adopted, they are then required to be filed with the IRS application Form 1023 seeking 501(c)(3) nonprofit status.
Following are direct links confirming that answer: The first, an IRS publication specifically indicates:
"The Internal Revenue Service requires the submission of organizational documents and bylaws, if
adopted, with an application for exemption under section 501(c)(3), and will review these documents to ensure that the applicant is organized exclusively for exempt purposes and that the applicant’s proposed or actual activities are consistent with those documents."
You may also confirm that bylaws are not required by the IRS to apply for recognition of tax-exempt, public charity status by reviewing Form 1023 (the application) and Publication 557 (the detailed instructions) from an IRS office. I have provided a link to the application, Form 1023, below:
Following is a public domain link that details Colorado requirements indicating that only Articles of Incorporation are necessary:
You may also find the publication "Governance of Nonprofits" offered by the Society of Corporate Secretaries and Governance Professionals of special interest:
If you would like further clarification, please let me know.