If I paid for and started a 501c3 by myself but I'm no longer a part of the organization can I still file those taxes?

No, TurboTax doesn't support Form 990, but you can download it from the IRS:

• Tax-exempt organizations with annual gross receipts totaling $200,000+ (or assets totaling $500,000+) should file Form 990
• Tax-exempt organizations with annual gross receipts under $200,000 and total assets under $500,000 should file Form 990-EZ
• If your annual gross receipts don't exceed $50,000, you can e-file Form 990-N
• Private foundations should file Form 990-PF

Note: Form 990 must be e-filed.

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