ORIGINAL REFERENCES
Read the source.
Government publications and guidance linked from the guides. Read the applicable year and effective dates before relying on a rule.
IRS: Publication 505, Tax Withholding and Estimated Tax ↗IRS: Publication 583, Starting a Business and Keeping Records ↗IRS: Publication 541, Partnerships ↗IRS: Instructions for Form 1120-S — Shareholder Reporting ↗IRS Publication 946: Depreciation Conventions ↗IRS: Publication 560, Retirement Plans for Small Business ↗IRS: Publication 15, Employer’s Tax Guide ↗IRS Publication 538: Accounting Methods ↗IRS: Independent Contractor or Employee ↗IRS Publication 463: Business Gifts ↗IRS: Tangible Property Final Regulations ↗IRS: Information Return Reporting ↗IRS: Instructions for Form 2210 ↗IRS: Publication 544, Sales and Other Dispositions of Assets ↗IRS Publication 334: Taxes ↗IRS: Publication 547, Casualties, Disasters, and Thefts ↗IRS: Estimated taxes ↗IRS: Credits and Deductions for Businesses ↗IRS: About Form 3800, General Business Credit ↗IRS: Get an extension to file your tax return ↗IRS: About Form 4868 ↗IRS: About Form 7004 ↗IRS: Direct Pay help ↗IRS: Online account for individuals ↗IRS: Online account frequently asked questions ↗IRS: Instructions for Form 172, Net Operating Losses ↗IRS: About Form 172 ↗IRS: S corporation stock and debt basis ↗IRS: Recordkeeping ↗IRS: Digital Assets ↗IRS: Publication 526, Charitable Contributions ↗IRS: About Form 3115 ↗IRS: Instructions for Form 3115 ↗IRS: Instructions for Form 8300 ↗IRS: Form 8300 reference guide ↗IRS: Backup withholding B program ↗IRS: Publication 1281 ↗IRS: Backup withholding ↗IRS: Disaster assistance and emergency relief ↗IRS: FAQs for disaster victims ↗IRS: Reconstructing records after a disaster ↗IRS Publication 551: Basis of Assets ↗IRS: Preparing for a disaster ↗IRS: Topic 453, Bad Debt Deduction ↗IRS: Income and Expenses FAQ, Travel Meals ↗IRS: Questions and Answers About the Limitation on Business Interest Expense ↗IRS: Qualified Business Income Deduction ↗IRS: Instructions for Form 8995 ↗IRS: Instructions for Form 8995-A ↗IRS: Publication 587, Business Use of Your Home ↗IRS: Topic 509, Business Use of Home ↗IRS: Instructions for Form 8829 ↗IRS: Topic 554, Self-Employment Tax ↗IRS: Instructions for Schedule SE ↗IRS: Questions and Answers for Additional Medicare Tax ↗IRS: Instructions for Form 8959 ↗IRS: Net Investment Income Tax ↗IRS: Instructions for Form 8960 ↗IRS: Topic 513, Work-Related Education Expenses ↗IRS: Publication 970, Tax Benefits for Education ↗IRS Form 4562 Instructions ↗IRS: Retirement Plans Startup Costs Tax Credit ↗IRS: Instructions for Form 8881 ↗IRS: Instructions for Form 3800 and Schedule A ↗IRS: Small Business Health Care Tax Credit and SHOP Marketplace ↗IRS: Instructions for Form 8941 ↗IRS: Determining FTEs and Average Annual Wages ↗IRS: Topic 511, Business Travel Expenses ↗IRS: Publication 4681, Canceled Debts ↗IRS: Instructions for Form 982 ↗IRS: Topic 432, Cancellation of Debt ↗IRS: Topic 556, Alternative Minimum Tax ↗IRS: Instructions for Form 6251 ↗IRS: Publication 925, Passive Activity and At-Risk Rules ↗IRS: Instructions for Form 8582 ↗IRS Schedule C Instructions: Legal and Professional Services ↗IRS Income and Expenses FAQs ↗IRS Publication 525: Repayments ↗IRS Form 1120 Instructions ↗IRS Publication 542: Corporations ↗IRS Form 461 Instructions ↗IRS Excess Business Losses: Limitation Ordering and Carryforward ↗IRS Internal Revenue Manual: Legal and Professional Fees ↗IRS Form 6765 Instructions: Section 174A ↗IRS Revenue Procedure 2025-28 ↗IRS Revenue Procedure 2026-32 ↗IRS Final Regulations: Section 162(f) ↗IRS Section 6050X Reporting Questions and Answers ↗IRS Form 1098-F Instructions ↗IRS: Amended and superseding corporate returns ↗IRS: Instructions for Form 1120-X ↗IRS: Employment taxes and the trust fund recovery penalty ↗IRS: Notice 784 ↗IRS: Payment plans and installment agreements ↗IRS: Payment options ↗IRS: Form 2210 and Schedule AI ↗IRS: Instructions for Form 4466 ↗IRS: Form 4466 ↗IRS: Understanding your CP2000-series notice ↗IRS: Topic 652, Notice of underreported income ↗IRS: Topic 651, Notices — what to do ↗IRS: Report identity theft for a business ↗IRS: Form 14039-B ↗IRS: If you received an EIN you did not request ↗