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 (Print version PDF | eBook EPUB) 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 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) or Section 521 of the Internal Revenue Code Taxpayer Advocate Service Other current products