The IRS is a bureau of the U.S. Department of the Treasury that collects federal income taxes and enforces tax law

The Internal Revenue Service (IRS) is the federal agency responsible for collecting income taxes from individuals and businesses, and for enforcing the Internal Revenue Code—the set of laws that govern how much tax you owe. It is not a separate government; it is a division of the Treasury Department, which handles all federal money. When you file a tax return, you send it to the IRS. When the IRS audits a return or sends you a notice about taxes owed, that notice comes from the IRS.

The IRS has regional offices across the country, but you do not typically visit one in person. Most contact happens by mail, phone, or through the IRS website at irs.gov. The agency employs revenue agents (who audit returns), tax examiners (who review specific issues), and customer service representatives who answer questions about filing and payments.

Key Takeaways

  • The IRS is part of the Treasury Department and collects federal income taxes from individuals and businesses under the rules of the Internal Revenue Code.
  • The IRS processes tax returns, issues refunds, sends notices about taxes owed, and conducts audits when returns are selected for review.
  • You can contact the IRS by phone, mail, or through irs.gov; visiting an office in person is rarely necessary and usually requires an appointment.
  • The IRS has no authority over state or local taxes—those are handled by your state revenue department or local tax authority.
  • If you receive a notice from the IRS, it will have a specific reason printed on it and instructions for how to respond.

What the IRS does with your tax return

When you file a federal tax return, the IRS receives it and processes it—meaning staff members or automated systems check that your numbers add up, that you reported all required income, and that you claimed only the deductions and credits you are may have access to to claim. If everything matches their records (your W-2s, 1099s, and other income documents), your return is accepted and any refund is issued. This process usually takes several weeks.

If something does not match or looks unusual, the IRS may send you a notice asking for more information or proposing a change to your return. Not all notices mean you made a mistake; sometimes the IRS straightforward needs clarification. Other times, the IRS selects a return for audit, which means a revenue agent will examine your records in detail to verify that what you reported is correct.

How the IRS decides to audit a return

The IRS does not audit every return. It uses computer programs to score returns based on patterns—for example, if your reported business expenses are unusually high compared to your income, or if you claim a large charitable deduction relative to your income level. Returns with higher scores are more likely to be selected for audit. The IRS also audits returns selected at random, and it may audit returns if it is investigating a specific issue, such as unreported income or a fraudulent claim.

If your return is selected for audit, the IRS will send you a letter explaining what it wants to examine and what records you need to provide. Some audits are handled entirely by mail; others require you to meet with an agent in person or by video call. You have the right to representation—you can bring a tax professional, attorney, or certified public accountant to an audit on your behalf.

IRS notices and what they mean

An IRS notice is a letter that tells you the agency has taken an action or needs information from you. Common notices include a bill for taxes owed, a notification that your refund will be delayed, a request for missing documents, or a proposed change to your return. Every notice includes a reason code and an explanation of why you received it, along with instructions for how to respond.

If you disagree with an IRS notice, you have the right to appeal. The notice itself will explain how to request an appeal and what important date you must meet. You do not have to hire a professional to appeal, but many people do because the process involves detailed tax law. If you cannot pay a bill the IRS sends, you can request a payment plan or an offer in compromise (a settlement for less than you owe), though not all requests are granted.

The difference between the IRS and state and local tax agencies

The IRS collects only federal income tax. Your state may have its own income tax, and your city or county may have a local income tax or wage tax. These are collected by separate state and local agencies—for example, the New York State Department of Taxation and Finance, or the Philadelphia Department of Revenue. If you owe state or local taxes, you will receive notices from those agencies, not from the IRS.

Some people owe taxes to both the IRS and their state. You file separate returns to each agency, and each one has its own rules about deductions, credits, and important date. If you move to a different state, you may need to file a return in both your old state and your new state for the year you moved, depending on when you moved and your state's rules.

How to contact the IRS

The main IRS phone line is 1-800-829-1040 for individual tax questions. Wait times are often long, especially during tax season (January through April). You can also visit irs.gov to read forms, read publications, check the status of a refund, or use the IRS's online tools. The website has a search function and a "Contact Us" page that directs you to the right department based on your question.

If you need to send documents to the IRS, the address depends on what you are sending and where you live. The notice you receive will include the correct mailing address. Do not send original documents unless the IRS specifically asks for them; send copies instead. Keep copies of everything you send for your own records.

When to hire a tax professional to deal with the IRS

You can represent yourself in dealings with the IRS, but some situations benefit from professional help. If you receive an audit notice, a bill you do not understand, or a notice proposing a large change to your return, a tax professional—such as a certified public accountant (CPA), enrolled agent (EA), or tax attorney—can review your situation and respond on your behalf. They can also represent you at an audit or appeal.

If your tax situation is straightforward (you have a W-2 job, take the standard deduction, and have no business income), you may not need professional help. If you have self-employment income, rental property, investments, or a complex family situation, professional guidance when you file can prevent problems later. If the IRS has already contacted you, a professional can often resolve the issue faster than you can on your own.

Frequently Asked Questions

Can the IRS come to my house or business?

Yes, but only in specific situations. Revenue agents can visit your home or business if you are being audited and the IRS needs to examine records on-site—for example, if you claim a home office deduction or run a business from your home. The IRS will send you a notice first. You can ask to move the meeting to an IRS office or conduct it by phone or video instead.

What happens if I ignore an IRS notice?

Ignoring an IRS notice does not make it go away. If you owe taxes and do not respond, the IRS can place a lien on your property, garnish your wages, or seize your bank account. If you received a notice but do not understand it or disagree with it, contact the IRS or a tax professional right away. Most notices include a important date for response.

Does the IRS ever call or text me?

The IRS does not initiate contact by phone or text to demand payment or threaten arrest. If someone calls claiming to be from the IRS and threatening legal action, it is a scam. Hang up and report it to the Treasury Inspector General for Tax Administration (TIGTA) at tigta.gov. The IRS contacts people by mail first, not by phone.

Can I get my taxes back if the IRS made a mistake?

Yes. If the IRS made an error on your return or in a notice, you can file an amended return (Form 1040-X) to correct it. You have three years from the original filing date to claim a refund. If the IRS made the error, you can also request abatement of penalties and interest in some cases. A tax professional can help you determine whether an amendment is necessary.

What is the difference between an IRS audit and an IRS investigation?

An audit is a review of your return to verify that the numbers are correct. An investigation is a criminal inquiry into whether you intentionally broke tax law—for example, by hiding income or claiming false deductions. Investigations are rare and are handled by the IRS Criminal Investigation division. If you are under investigation, you should contact a tax attorney when ready.