I'll give you the basic steps for an independent 501c3 (eg PTO). You should check with your state PTA or call the IRS tax-exempt help line to see whether there are any additional or different procedures because you fall under the PTA umbrella.
You indicated that your group is incorporated, so the first step is to amend your articles of incorporation (and bylaws) and file them with the state corporations office. For the IRS, you can report the name change on your annual Form 990. You should also attach the amended articles of incorporation and bylaws.
The final step is to request an amended determination letter (which states your exemption) from the IRS. This step may be different for you, because you are covered under the PTA group exemption.
The IRS nonprofit help line is (877) 829-5500. We've found them them to be quite helpful.
Oh, and there's no IRS fee. I believe some states charge a small filing fee for amending corporation papers.
- Craig
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