Sources

Every substantive procedural statement on this site is supported by primary authority. This index is generated from the pages themselves, so it cannot drift from what they actually cite.

59 distinct sources are cited across the site, of which 59 are primary authority — the Internal Revenue Code as published by the Office of the Law Revision Counsel, the Internal Revenue Manual, IRS publications, IRS forms, and IRS guidance pages. The build rejects any content page that does not cite at least one primary source.

The "checked" date is when the citation was last verified against the live document by an explicit verification task, which reports dead links and silent redirects. That task is deliberately not part of the ordinary build, so that an IRS outage cannot stop the site compiling. See the editorial policy for the sourcing rules, including how statutory constants and revisable administrative figures are treated differently.

Internal Revenue Code

• 26 U.S.C. § 6020 — Returns prepared for or executed by Secretary Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP14 notice , LT16 notice , Unfiled returns
• 26 U.S.C. § 6159 — Agreements for payment of tax liability in installments Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: Installment agreement , Partial pay installment agreement , Resolution options
• 26 U.S.C. § 6303 — Notice and demand for tax Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP14 notice , How IRS collection works
• 26 U.S.C. § 6320 — Notice and opportunity for hearing upon filing of notice of lien Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP14 notice , CP504 notice , Federal tax lien , How IRS collection works , IRS notices
• 26 U.S.C. § 6321 — Lien for taxes Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP504 notice , Federal tax lien , How IRS collection works
• 26 U.S.C. § 6323 — Validity and priority against certain persons Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP504 notice , Federal tax lien , How IRS collection works
• 26 U.S.C. § 6325 — Release of lien or discharge of property Office of the Law Revision Counsel, U.S. House of Representatives · checked September 24, 2026 Cited by: Federal tax lien
• 26 U.S.C. § 6330 — Notice and opportunity for hearing before levy Office of the Law Revision Counsel, U.S. House of Representatives · checked September 24, 2026 Cited by: CP14 notice , CP503 notice , CP504 notice , CP501 notice , CP90 notice , LT11 notice , Federal tax lien , How IRS collection works , IRS notices , IRS levy , Wage garnishment
• 26 U.S.C. § 6331 — Levy and distraint Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP503 notice , CP504 notice , LT11 notice , How IRS collection works , IRS levy , Wage garnishment
• 26 U.S.C. § 6332 — Surrender of property subject to levy Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: LT11 notice , IRS levy , Wage garnishment
• 26 U.S.C. § 6334 — Property exempt from levy Office of the Law Revision Counsel, U.S. House of Representatives · checked September 24, 2026 Cited by: CP90 notice , LT11 notice , How IRS collection works , IRS levy , When you can't pay , Owing the IRS , Wage garnishment
• 26 U.S.C. § 6343 — Authority to release levy and return property Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: Currently Not Collectible , Installment agreement , How IRS collection works , IRS levy , When you can't pay , Wage garnishment
• 26 U.S.C. § 6404 — Abatements Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: Penalty abatement
• 26 U.S.C. § 6502 — Collection after assessment Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: Currently Not Collectible , How IRS collection works , Partial pay installment agreement , When you can't pay , Owing the IRS , Tax investigation , Resolution options
• 26 U.S.C. § 6511 — Limitations on credit or refund Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: LT16 notice , Unfiled returns
• 26 U.S.C. § 6601 — Interest on underpayment, nonpayment, or extensions of time for payment, of tax Office of the Law Revision Counsel, U.S. House of Representatives · checked September 24, 2026 Cited by: CP14 notice , Currently Not Collectible , Installment agreement , Penalty abatement , Owing the IRS
• 26 U.S.C. § 6651 — Failure to file tax return or to pay tax Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: CP14 notice , Installment agreement , Penalty abatement , Owing the IRS , Unfiled returns
• 26 U.S.C. § 7122 — Compromises Office of the Law Revision Counsel, U.S. House of Representatives · checked September 23, 2026 Cited by: Offer in Compromise , Resolution options
• 26 U.S.C. § 7203 — Willful failure to file return, supply information, or pay tax Office of the Law Revision Counsel, U.S. House of Representatives · checked September 25, 2026 Cited by: Unfiled returns

Internal Revenue Manual

• Internal Revenue Manual 20.1.1, Introduction and Penalty Relief Internal Revenue Service · checked September 23, 2026 Cited by: Penalty abatement
• Internal Revenue Manual 4.12.1, Nonfiled Returns Internal Revenue Service · checked September 24, 2026 Cited by: Unfiled returns
• Internal Revenue Manual 5.14.1, Securing Installment Agreements (Payment Plans) Internal Revenue Service · checked September 23, 2026 Cited by: Installment agreement , Partial pay installment agreement
• Internal Revenue Manual 5.16.1, Currently Not Collectible Internal Revenue Service · checked September 23, 2026 Cited by: Currently Not Collectible , When you can't pay
• Internal Revenue Manual 5.19.17, Campus Procedures for Currently Not Collectible and Offers in Compromise Internal Revenue Service · checked September 23, 2026 Cited by: Currently Not Collectible
• Internal Revenue Manual 5.8.5, Financial Analysis Internal Revenue Service · checked September 23, 2026 Cited by: Offer in Compromise
• IRM Procedural Update SBSE-20-0626-0643, Automatic Exemption From Penalty Administrative Relief Internal Revenue Service · checked September 24, 2026 Cited by: Penalty abatement

IRS publications

• Publication 1494, Tables for Figuring Amount Exempt from Levy on Wages, Salary, and Other Income Internal Revenue Service · checked September 23, 2026 Cited by: Wage garnishment
• Publication 1660, Collection Appeal Rights Internal Revenue Service · checked September 23, 2026 Cited by: CP504 notice , CP90 notice , Federal tax lien , IRS notices
• Publication 594, The IRS Collection Process Internal Revenue Service · checked September 23, 2026 Cited by: CP14 notice , CP503 notice , CP501 notice , How IRS collection works , IRS notices , Owing the IRS , Tax investigation , Resolution options

IRS forms

• About Form 843, Claim for Refund and Request for Abatement Internal Revenue Service · checked September 23, 2026 Cited by: Penalty abatement
• Form 12153, Request for a Collection Due Process or Equivalent Hearing Internal Revenue Service · checked September 23, 2026 Cited by: CP90 notice , LT11 notice
• Form 433-A (OIC), Collection Information Statement for Wage Earners and Self-Employed Individuals Internal Revenue Service · checked September 23, 2026 Cited by: Offer in Compromise
• Form 433-F, Collection Information Statement Internal Revenue Service · checked September 23, 2026 Cited by: Currently Not Collectible , When you can't pay
• Form 656-B, Offer in Compromise Booklet Internal Revenue Service · checked September 23, 2026 Cited by: Offer in Compromise

IRS guidance pages

• Administrative penalty relief Internal Revenue Service · checked September 23, 2026 Cited by: Penalty abatement
• Collection Due Process (CDP) FAQs Internal Revenue Service · checked September 23, 2026 Cited by: CP90 notice , LT11 notice
• Collection financial standards Internal Revenue Service · checked September 23, 2026 Cited by: Currently Not Collectible , Offer in Compromise , Partial pay installment agreement , When you can't pay , Tax investigation , Resolution options
• Filing past due tax returns Internal Revenue Service · checked September 23, 2026 Cited by: LT16 notice , Unfiled returns
• Information about bank levies Internal Revenue Service · checked September 23, 2026 Cited by: IRS levy
• Information about wage levies Internal Revenue Service · checked September 23, 2026 Cited by: Wage garnishment
• Levy Internal Revenue Service · checked September 23, 2026 Cited by: IRS levy
• Offer in compromise Internal Revenue Service · checked September 23, 2026 Cited by: Offer in Compromise
• Online payment agreement application Internal Revenue Service · checked September 23, 2026 Cited by: Installment agreement
• Payment plans; installment agreements Internal Revenue Service · checked September 23, 2026 Cited by: Installment agreement , Partial pay installment agreement
• Penalty relief for reasonable cause Internal Revenue Service · checked September 23, 2026 Cited by: Penalty abatement
• Taxpayer Bill of Rights Internal Revenue Service · checked September 23, 2026 Cited by: How IRS collection works , Tax investigation
• Topic no. 201, The collection process Internal Revenue Service · checked September 23, 2026 Cited by: CP503 notice , CP501 notice , LT16 notice , How IRS collection works , IRS notices , Owing the IRS
• Topic no. 202, Tax payment options Internal Revenue Service · checked September 23, 2026 Cited by: When you can't pay , Resolution options
• Transcript types for individuals and ways to order them Internal Revenue Service · checked September 23, 2026 Cited by: LT16 notice , Tax investigation , Unfiled returns
• Understanding a federal tax lien Internal Revenue Service · checked September 23, 2026 Cited by: Federal tax lien
• Understanding your CP14 notice Internal Revenue Service · checked September 23, 2026 Cited by: CP14 notice
• Understanding your CP501 notice Internal Revenue Service · checked September 23, 2026 Cited by: CP501 notice
• Understanding your CP503 notice Internal Revenue Service · checked September 23, 2026 Cited by: CP503 notice
• Understanding your CP504 notice Internal Revenue Service · checked September 23, 2026 Cited by: CP504 notice
• Understanding your CP523 notice Internal Revenue Service · checked September 23, 2026 Cited by: Installment agreement
• Understanding your CP90 notice Internal Revenue Service · checked September 23, 2026 Cited by: CP90 notice
• Understanding your LT11 notice or Letter 1058 Internal Revenue Service · checked September 23, 2026 Cited by: LT11 notice
• Understanding your LT16 notice Internal Revenue Service · checked September 23, 2026 Cited by: LT16 notice
• Your account Internal Revenue Service · checked September 23, 2026 Cited by: Owing the IRS , Tax investigation