This publication covers the rules for the tax on unrelated business income of exempt organizations. It explains: which organizations are subject to the tax, what the requirements are for filing a tax return, what an unrelated trade or business is, and how to figure unrelated business taxable income. Current Revision Publication 598 (PDF PDF | HTML | eBook) Recent Developments None at this time. Other Items You May Find Useful All Revisions for Publication 598 About Form 990-T, Exempt Organization Business Income Tax Return About Form 990-W, Estimated Tax on Unrelated Business Taxable Income for Tax-Exempt Organizations About Form 1023, Application for Recognition of Exemption Under Section 501(c)(3) of the Internal Revenue Code About Form 1024-A, Application for Recognition of Exemption Under Section 501(c)(4) of the Internal Revenue Code About Form 1024, Application for Recognition of Exemption Under Section 501(a) Taxpayer Advocate Service Other Current Products