IRS: Frequently Asked Questions

The Internal Revenue Service administers federal tax law for more than 150 million individual filers and millions of business entities each year, generating questions that span filing obligations, audit exposure, debt resolution, and taxpayer rights. This page addresses the most common points of confusion across those categories — from how the IRS classifies income and selects returns for examination, to what triggers formal enforcement action and where authoritative guidance can be found. Each answer is grounded in statute, IRS administrative guidance, or published agency policy.

What are the most common issues encountered?

Filing errors, missed deadlines, and unreported income account for the largest share of taxpayer problems with the IRS. The agency's Notices Explained resource lists CP2000 — a notice of proposed changes based on information-return mismatches — as one of the highest-volume correspondence types the IRS issues annually.

The 4 categories that generate the most taxpayer contact with the agency are:

1. Underreported income — Third-party forms (W-2, 1099-NEC, 1099-K) reported to the IRS that do not match a filed return.
2. Missed estimated tax payments — Particularly common among self-employed individuals and gig workers subject to self-employment tax obligations.
3. Unfiled returns — The IRS may file a Substitute for Return (SFR) under IRC § 6020(b) when a required return is not submitted, typically generating a higher liability than a filed return would.
4. Identity theft — The IRS flagged more than 1 million tax returns for identity theft screening in fiscal year 2022 (IRS Data Book 2022).

How does classification work in practice?

The IRS classifies income, entities, and transactions to determine which tax rules apply. Worker classification — whether an individual is an employee or an independent contractor — is one of the most contested areas. The IRS applies a behavioral control, financial control, and relationship-type test (the "common law" test, explained in IRS Publication 15-A) to distinguish the two categories.

Employee vs. Independent Contractor — key distinctions:

Misclassification carries significant employer exposure: the trust fund recovery penalty under IRC § 6672 holds responsible parties personally liable for 100% of undeposited payroll taxes. Entity classification — sole proprietor, S corporation, C corporation, partnership — similarly determines which federal tax types apply to business income.

What is typically involved in the process?

A standard tax filing cycle begins with gathering income documents, selecting the correct filing status, and calculating gross income, adjustments, deductions, and credits. The IRS e-File system processed more than 150 million returns electronically in fiscal year 2023 (IRS Filing Season Statistics).

The core sequence for individual filers:

1. Choose between the standard deduction or itemized deductions.
2. Apply applicable tax credits to reduce tax owed.
3. File by the statutory deadline (April 15 for most individual filers) or request an extension.
4. Pay any balance due or track the refund process.

What are the most common misconceptions?

Filing an extension extends the payment deadline. It does not. An extension grants additional time to file the return but not additional time to pay. Interest accrues on unpaid balances from the original due date under IRC § 6601.

An audit always means criminal investigation. The vast majority of audits are civil matters — correspondence audits conducted entirely by mail. The IRS Criminal Investigation Division opens roughly 2,000–3,000 cases per year against a backdrop of more than 150 million filed returns; the overlap is statistically small.

The IRS can collect indefinitely. The general statute of limitations for collection is 10 years from the date of assessment under IRC § 6502. The IRS Statute of Limitations page covers the events that can toll or extend that window.

A refund means the return will not be audited. The IRS has 3 years from the filing date (or due date, whichever is later) to assess additional tax under IRC § 6501, regardless of whether a refund was issued.

Where can authoritative references be found?

The primary public sources for IRS rules and guidance are:

• Internal Revenue Code (IRC) — Title 26 of the United States Code, available at uscode.house.gov.
• IRS Publications — Plain-language explanations of specific topics, catalogued at irs.gov/forms-pubs. Publication 17 covers individual income tax comprehensively.
• Internal Revenue Manual (IRM) — The IRS's own procedural guide for employees, publicly available at irs.gov/irm. IRM Part 5 covers collection; IRM Part 4 covers examination.
• Treasury Regulations — Legally binding interpretations of the IRC, published in the Code of Federal Regulations (CFR) Title 26, accessible at ecfr.gov.
• IRS Online Account — Taxpayers can access transcripts, payment history, and notices through the IRS Online Account portal.

The IRS Forms and Publications index on this site organizes the most frequently needed documents by topic.

How do requirements vary by jurisdiction or context?

Federal tax obligations under the IRC apply uniformly across all 50 states. However, state income tax regimes impose independent filing requirements that differ substantially. 9 states — including Texas, Florida, and Nevada — impose no state individual income tax, while California's top marginal rate reached 13.3% (California Franchise Tax Board).

Context also determines which federal rules apply:

• International taxpayers face additional reporting under FATCA (Foreign Account Tax Compliance Act) and FinCEN Form 114 (FBAR), addressed in detail at Foreign Account Reporting and International Tax Compliance.
• Nonprofit organizations are exempt from income tax under IRC § 501(c) but must satisfy annual reporting requirements via Form 990. Nonprofit Compliance covers the operative rules.
• Gig economy workers face distinct withholding and estimated-payment obligations compared to traditional W-2 employees, covered at Gig Economy Tax Requirements.
• Estates and trusts are taxed under Subchapter J of the IRC, with Estate and Gift Tax rules applying separately to transfers.

What triggers a formal review or action?

The IRS uses the Discriminant Function System (DIF) to score returns statistically; returns with high DIF scores — indicating income or deduction patterns that deviate significantly from similar returns — are more likely to be selected for examination. The IRS Audit Selection Criteria page details the documented selection methods.

Beyond statistical scoring, 5 specific triggers consistently generate IRS attention:

1. Substantial unreported income — Mismatches between 1099 or W-2 data and the filed return.
2. Large charitable deductions relative to income — Deductions disproportionate to AGI.
3. Home office deductions — Particularly when claimed by individuals who also receive W-2 wages.
4. Cash-intensive businesses — Schedule C returns with high revenue and low reported profit margins.
5. Failure to file — The IRS cross-references third-party information returns to identify non-filers and may issue a notice or assess a Substitute for Return.

Once a formal examination begins, the IRS Audit Process proceeds through correspondence, office, or field audit channels depending on the complexity and dollar amount at issue. Unresolved audit findings can escalate to the IRS Appeals Process before litigation is considered.

How do qualified professionals approach this?

Tax attorneys, Certified Public Accountants (CPAs), and Enrolled Agents (EAs) — the three categories of federally authorized representatives under Treasury Circular 230 — approach IRS matters through a structured analysis of facts, applicable code sections, and administrative options.

For collection matters, practitioners typically:

• Pull IRS Transcripts to establish the full account history, including assessment dates, payment credits, and lien recordings.
• Evaluate eligibility for resolution options including Installment Agreements, Offer in Compromise, Currently Not Collectible status, or Penalty Abatement.
• Assess whether Innocent Spouse Relief applies when joint liability is contested.
• Engage the Taxpayer Advocate Service when normal IRS channels fail to resolve hardship cases within statutory timeframes.

For audit matters, representatives review documentation before any IRS contact, limit the scope of information provided to what is directly requested, and exercise appeal rights at every available stage. The home page of this site provides a structured starting point for navigating the full range of IRS topics covered across this reference.

Practitioners distinguish between a correspondence audit — resolved entirely by mail, typically addressing a single line item — and a field audit, which involves an IRS Revenue Agent conducting an in-person examination of books and records. IRS Correspondence Audits and IRS Field Audits each carry distinct documentation standards and procedural timelines that shape the professional approach.