Tax Research

USC Title 26: Internal Revenue Code

Internal Revenue Code

IRC Code Section Structure:

Section number - 4711 (g) (2) (B) (ii) (III)
Subsection            (g)
Paragraph                 (2)
Subparagraph                  (B)
Clause                            (ii)
Subclause                              (III)

Income Tax Sections:

§§ 1-59B Determination of Tax Liability
§§ 61-291 Computation of Taxable income
§§ 301-385 Corporate Distributions and Adjustments
§§ 401-436 Deferred Compensation, etc.
§§ 441-483 Accounting Periods and Methods of Accounting
§§ 501-530 Exempt Organizations
§§ 531-565 Corporations Used to Avoid Income Tax on Shareholders
§§ 581-597 Banking institutions
§§ 611-638 Natural Resources
§§ 641-692 Estates, Trusts, Beneficiaries, and Decedents
§§ 701-777 Partners and Partnerships
§§ 801-848 Insurance Companies
§§ 851—860L Regulated investment Companies and Real Estate investment Trusts
§§ 861-999 Tax Based on Income From Sources Within or Without the United States
§§ 1001-1111 Gain or Loss on Disposition of Property
§§ 1201-1298 Capital Gains and Losses
§§ 1361-1379 Tax Treatment of S Corporations and Their Shareholders
§ 1401- Tax on Self-Employment Income
§ 1441- Withholding of Tax on Nonresident Aliens and Foreign Corporations
§ 1501- Consolidated Returns

Other Sections:

§ 2001- Estate and Gift Taxes
§ 3101- Employment Taxes
§ 4001- Miscellaneous Excise Taxes
§ 5001- Alcohol, Tobacco, and Certain Other Excise Taxes
§ 6001- Procedure and Administration
§ 8001- The Joint Committee on Taxation
§ 9001- Financing of Presidential Election Campaigns
§ 9501- Trust Fund Code

Treasury Regulations

REG  = Regulation
T.D. = Treasury Decision

Form:    Reg. §  1   . 4711 . -xxx

Part number -    1      
Section number -       4711
Subdivisions -                 -...

Part Numbers:
1     Income Tax
20    Estate Tax
25    Gift Tax
31    Employment Tax
48/49 Excise Tax

IRS: IRS: Internal Revenue Bulletins

IRS: IRS: Revenue Rulings


USC Title 31: Money and Finance: Treasury

§ 0-50 Office of the Secretary of the Treasury
§ 51-199 Monetary Offices
§ 200-399 Fiscal Service
§ 400-499 Secret Service
§ 500-599 Office of Foreign Assets Control
§ 600-699 Bureau of Engraving and Printing
§ 700-799 Federal Law Enforcement Training Center
§ 800-899 Office of Investment Security
§ 900-999 Federal Claims Collection Standards
§ 1000-1099 FINCEN Financial Crimes Enforcement Network


Tax Research


Tax Politics


Liberal Tax Politics


U. S. Code

Title 1 General Provisions
Title 2 The Congress
Title 3 The President
Title 4 Flag and Seal, Seat of Govemment
Title 5 Government Organization and Employees
Title 6 Domestic Security
Title 7 Agriculture
Title 8 Aliens and Nationality
Title 9 Arbitration
Title 10 Armed Forces
Title 11 Bankruptcy
Title 12 Banks and Banking
Title 13 Census
Title 14 Coast Guard
Title 15 Commerce and Trade
Title 16 Conservation
Title 17 Copyrights
Title 18 Crimes and Criminal Procedure
Title 19 Customs Duties
Title 20 Education
Title 21 Food and Drugs
Title 22 Foreign Relations and Intercourse
Title 23 Highways
Title 24 Hospitals and Asylums
Title 25 Indians
Title 26 Internal Revenue Code
Title 27 Intoxicating Liquors
Title 28 Judiciary and Judicial Procedure
Title 29 Labor
Title 30 Mineral Lands and Mining
Title 31 Money and Finance
Title 32 National Guard
Title 33 Navigation and Navigable Waters
Title 34 Navy (repealed)
Title 35 Patents
Title 36 Patriotic Societies and Observances
Title 37 Pay and Allowances of the Uniformed Services
Title 38 Veterans' Benefits
Title 39 Postal Service
Title 40 Public Buildings, Properly, and Works
Title 41 Public Contracts
Title 42 The Public Health and Welfare
Title 43 Public Lands
Title 44 Public Printing and Documents
Title 45 Railroads
Title 46 Shipping
Title 47 Telegraphs, Telephones, and Radiotelegraphs
Title 48 Territories and insular Possessions
Title 49 Transportation
Title 50 War and National Defense

U. S. Courts of Appeals

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Tax Details

Enrolled Agent



Treasury Department Circular 230

Part 10: Practice Before The Internal Revenue Service
Duties and Restrictions Relating to
Practice Before the Internal Revenue Service:
§ 10.20 Information to be furnished
§ 10.21 Knowledge of client's omission
§ 10.22 Diligence as to accuracy
§ 10.23 Prompt disposition of pending matters
§ 10.24 Assistance from or to disbarred or suspended persons and former Internal Revenue Service employees
§ 10.25 Practice by former government employees, their partners and their associates
§ 10.26 Notaries
§ 10.27 Fees
§ 10.28 Return of client's records
§ 10.29 Conflicting interests
§ 10.30 Solicitation
§ 10.31 Negotiation of taxpayer checks
§ 10.32 Practice of law
§ 10.33 Best practices for tax advisors
§ 10.34 Standards with respect to tax returns and documents, affidavits and other papers
§ 10.35 Competence
§ 10.36 Procedures to ensure compliance
§ 10.37 Requirements for written advice
§ 10.38 Establishment of advisory committees

IRS Rejection Codes

IRS Reject Codes
500 Primary SSN and Primary Name Control of the Tax Form must match data from the IRS Master File
501 Qualifying SSN on Schedule EIC and the corresponding Qualified Name Control must match data from the IRS Master File
502 Employer Identification Number of Form W-2,W-2G, or 1099-R must match data from the IRS Master File
503 Last name for the secondary taxpayer on the return does not match the IRS Master File and/or SSA records
504 Dependent's SSN must match data from the IRS Master File
506 Qualifying child's SSN listed for the purpose of claiming Earned Income Tax Credit (EITC) has been used on another tax return
507 Dependent's SSN on the Form 1040 was previously used for the same purpose
535 Qualifying SSN on Schedule EIC and the corresponding Year of Birth must match data received from the SSA
541 Taxpayer must be older than qualifying child on Schedule EIC
600 Taxpayer must file Form 8862 to claim EITC after disallowance

IRS Letters

CP01Aa unique 6-digit IP PIN with instructions on how to use it. Mailed by IRS to taxpayers every December.
CP11Math Error on Return - Balance Due
CP12Understanding Your CP12 Notice
CP14Balance Due, No Math Error
CP15Civil Penalty Notice
CP15BCivil Penalty Notice for Trust Fund Recovery Penalty
CP15HShared Responsibility Payment Due
CP21AData Processing Adjustment Notice, Balance Due of
CP22AData Processing Adjustment Notice, Balance Due of
CP23Estimated Tax Credits Discrepancy - We Changed Your Return to Match Your Credits or Payments Posted to Your Account - Balance Due
CP23TEstimated Tax Discrepancy, Balance Due of $5 or More
CP47ATax Assessed- Notification of the Requested Credit Elect/Refund Being Applied to Section 965 Tax Liability
CP47BTax Assessed- Notification of a Credit Elect/Refund Being Applied to Section 965 Tax Liability
CP47CTax Assessed- Including Section 965 Tax Liability
CP51AWe've Calculated Your Income Tax For You - Balance Due
CP60We Removed a payment Erroneously Applied to Your Account. - Balance Due
CP94Criminal Restitution Final Demand Notice
CP101Math Error, Balance Due of $5 or More on Form 940
CP102Math Error, Balance Due of $5 or More on Forms 941, 941SS, 943, 944, 944SS, 945
CP103Math Error, Balance Due - Form CT-1
CP104Math Error, Balance Due of $5 or More - Form 720
CP105Math Error, Balance Due of $5 or More - Forms 11C, 2290, 706, 709, 730
CP107Math Error, Balance Due of $5 or More - Form 1042
CP126Math Error, Balance Due or Overpayment Less Than $1 on Forms 990PF, 4720, 5227
CP132Math Error, Balance Due on Forms 990C, 990T, 1041, 1120, 8804
CP134BFederal Tax Deposit(s) (FTD) Discrepancy - Balance Due
CP141LWe Charged a Penalty Under Internal Revenue Code Section 6652(c) - Form Filed Late
CP161No Math Error, Balance Due (Except Form 1065)
CP162Untimely Filing Penalty - Partnership
CP165Penalty Assessed for Dishonored Check
CP210Examination (Audit) or Data Processing Tax Adjustment - Balance Due, Overpayment, or Even Balance
CP215Civil Penalty - 500 and 600 Series
CP220Examination (Audit) or Data Processing Tax Adjustment - Balance Due, Overpayment, or Even Balance
CP220JEmployer Shared Responsibility Payment (ESRP) 4980H Adjustment - Balance Due, Even Balance or Overpayment Notice
CP230Combined Annual Wage Reporting - CAWR/DP Tax Adjustment Amended Return Filed
CP233J4980H Adjustment bal due, even bal or overpayment Notice (ESRP)
CP240Combined Annual Wage Reporting - CAWR/DP Discrepancy Tax Adjustment
CP260An Erroneous Payment Previously Applied to Your Account Has Been Reversed - Balance Due
CP283Penalty Charged on Your Form 5500 - Late or Incomplete Form
CP501You have a balance due (money you owe the IRS) on one of your tax accounts
CP503We have not heard from you and you still have an unpaid balance on one of your tax accounts
CP504You have an unpaid amount due on your account. If you do not pay the amount due immediately, the IRS will seize (levy) your state income tax refund and apply it to pay the amount you owe
CP711Spanish Math Error - Balance Due - Error en la Planilla - Saldo Adeudado
CP714Spanish Balance Due - No Math Error - Planilla Radicada - Saldo Adeudado
CP721AData Processing Adjustment Notice, Balance Due (Spanish) - Cambios a su Planilla - Saldo Adeudado
CP722ASpanish Data Processing Adjustment Notice, Balance Due of $5 or more - Cambios a su Planilla - Saldo Adeudado
CP802Spanish BMF Math Error, Balance Due of $5 or More on Forms 941PR, 943PR - Hemos Hecho Cambios a su Planilla Porque Creemos que hay un Error de Cálculo
CP834BFederal Tax Deposit(s) (FTD) Discrepancy - Balance Due (Spanish)
CP865Spanish Penalty for Dishonored Check on Forms 94XPR FTD
CP2000Understanding Your CP2000 Notice

IRS Collection Steps

  • CP 14 - Balance Due (CP stands for "Computer Paragraph")

    • 30-60 day

  • Installment Agreement

    • IRM Current returns for taxes must be filed and current deposits paid before an installment agreement can be approved and the taxpayer must remain tax compliant for the entire term of the installment agreement, or he/she will default the agreement. This includes the obligation to make estimated tax payments to avoid accruing new tax liabilities, that would default the agreement.

    • IRS: CP 89: Annual Installment Agreement Statement

  • Offer in Compromise (OIC), Form 656

    • Current returns for taxes must be filed and current deposits paid before an Offer in Compromise. This includes the obligation to make estimated tax payments to avoid accruing new tax liabilities, that would default the agreement.

  • CP 501 - Reminder, Balance Due

    • 30-60 day

  • CP 503 - 2nd Notice, Balance Due

    • 30-60 day

  • CP 504 - Final Notice, Balance Due

    • 30-60 day

  • CP 90 - Final Notice of Intent to Levy and Notice of Your Right to a Hearing Due

    • 30 days time to file an appeal

  • 668(Y)(c) - Notice of Federal Tax Lien

  • Appeals Collection Due Process (CDP) Hearing

  • CP 91 - Final Notice Before Levy on Social Security Benefits

    • 30 days time to prevent action

Government Associations

  • BBB Better Business Bureau
  • BLS Bureau of Labor Statistics
  • DHS Department of Homeland Security
  • DOL Department of Labor
  • FDIC Federal Deposit Insurance Corporation
  • FEMA Federal Emergency Management Agency
  • GPO Government Publishing Office
  • GSA General Services Administration
  • IRS Internal Revenue Service
  • RRB Railroad Retirement Board
  • SSA Social Security Administration
  • STATE Department of State
  • TREASURY U.S. Department of the Treasury
  • USCIS U.S. Citizenship and Immigration Services
  • USPS U.S. Postal Service
  • VA Veteran's Administration

National Associations

  • AAA-CPA The American Association of Attorneys - Certified Public Accountants
  • ABA American Bar Association - Section of Taxation
  • AICPA The American Institute of Certified Public Accountants
  • APA American Payroll Association
  • FTA Federation of Tax Administrators
  • NAEA National Association of Enrolled Agents
  • NACTP National Association of Computerized Tax Processors
  • NASBA National Association of State Boards of Accountancy
  • NATP National Association of Tax Professionals
  • NCCPAP National Conference of CPA Practitioners
  • NSA National Society of Accountants
  • NSTP National Society of Tax Professionals

Local Associations

Tax Preparation Companies

Banks, Brokerages

Payroll Processing Companies

Accounting Companies


  • SPEC - Stakeholder Partnerships, Education and Communication
  • VITA - Volunteer Income Tax Assistance
  • TCE - Tax Counseling for the Elderly (AARP)
  • QSR - Quality Site Requirements
  • VSC - Volunteer Standards of Conduct
  • SIDN - Site Identification Number
  • EFIN - Electronic Filing Identification Numbers
  • ERO - Electronic Return Originator
  • EITC - Earned Income Tax Credit
  • TIGTA - Treasury Inspector General for Tax Administration
  • PSO - Public Safety Officer
  • COD - Cancellation of Debt
  • PMI - Primary Mortgage Insurance
  • FATCA - Foreign Account Tax Compliance Act (out of scope)
  • RMD - Required Minimum Distribution after age 70.5
  • AOC - American Opportunity Credit
  • LLC - Lifetime Learning Credit
  • ABLE - Achieving a Better Life Experience
  • QOF - Qualified Opportunity Fund
  • QBI: Qualified business income
  • PTP: Qualified publicly traded partnership
  • REIT: Real estate investment trust




IRS Volunteer Resources

VITA/TCE Education

Training Materials

1. Volunteer Standards of Conduct

2. Intake/Interview and Quality Review

3. Basic

4. Advanced

5. Military

6. International

7. Health Savings Accounts (HSA) Test

9. Foreign Student

10. Puerto Rico

11. Site Coordinator


Wolfgang Barwig, EA