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Notice of Deficiency


A Notice of Deficiency is a formal written document issued by a tax authority, such as the Internal Revenue Service (IRS) in the U.S., indicating that there is an outstanding tax liability owed by the taxpayer. This notice provides a detailed report of any discrepancies found in a person’s tax return after an examination by the IRS and serves as a legal warning to the taxpayer. It also signifies the taxpayer’s right to contest the amount in court before payment.


The phonetic pronunciation for “Notice of Deficiency” is: “No-tis ov De-fi-shen-see”

Key Takeaways

1. Notification of Tax Due: A Notice of Deficiency, also known as a 90-day letter, is issued by the Internal Revenue Service (IRS) to inform a taxpayer about the amount of deficiency in their tax amount.

2. Legal Reference: It is an official legal notice, which includes a detailed report indicting the adjustments and how the tax amount was calculated. It is typically the final notice before legal action is taken and provides the taxpayer with the right to challenge the decision in Tax Court.

3. Time To Respond: Upon receiving the Notice of Deficiency, the taxpayers have 90 days (150 days if they live outside of the U.S) to file a petition in Tax Court to dispute the alleged deficiency. If the taxpayer fails to respond within the given time frame, the IRS will proceed with the proposed tax assessment.


The term “Notice of Deficiency” , primarily used in tax law, is crucial in business and finance due to its role in notifying taxpayers about unpaid back taxes. Specifically, a Notice of Deficiency is a formal written declaration issued by a tax authority, such as the Internal Revenue Service (IRS) in the United States, outlining the discrepancy between the tax reported by a taxpayer and the tax calculated by the agency. The significance of this notice is dual-faceted. On one hand, it serves as a crucial checkpoint allowing taxpayers an opportunity to challenge or rectify the specified discrepancy before legal action is initiated. On the other hand, from the perspective of the taxing authority, it is a legal prerequisite for enforcing collection of unpaid taxes. Failing to adequately respond to a notice of deficiency can result in legal ramifications and potential financial penalties, making it an essential part of tax law compliance for businesses and individuals.


A Notice of Deficiency is primarily an official document sent by tax authorities, like the Internal Revenue Service (IRS) in the U.S., to a taxpayer indicating undue tax payment or discrepancies in the taxpayer’s income tax return. This serves as an important tool in the taxation system as it aims to ensure fairness and accuracy in the taxation process. The standard purpose of a Notice of Deficiency is to serve as an alert for taxpayers about any flaws or misstatements in their tax return, providing them with an opportunity to rectify them before any legal consequences occur.The Notice gives taxpayers an overview of any unpaid amounts, including interest and penalties, and presents them with a chance to either agree with the calculated deficient amount and pay it or disagree and contest it in court. It ensures transparency between the taxpayer and the tax authority by fully outlining the calculations that resulted in the claimed deficiency. In essence, the Notice of Deficiency is used by tax authorities to enforce tax laws and hold taxpayers accountable, simultaneously providing taxpayers with a pathway to correct their tax filings and maintain compliance with tax regulations.


1. Tax Notice of Deficiency: The most common example is the Notice of Deficiency sent by the IRS (Internal Revenue Service) to taxpayers in the US. This occurs when the IRS has determined that a taxpayer owes more tax than they have paid or claimed on their tax return. The Notice of Deficiency is the official written notice, providing a 90-day timeframe for the taxpayer to either pay the additional amount or dispute it in Tax Court.2. Financial Institution Notice of Deficiency: If a bank or other financial institution detects discrepancies in a customer’s account statements or any shortfall in contractual payments, it may issue a notice of deficiency. For instance, if a borrower defaults on a mortgage payment, the lending bank may send a notice of deficiency stating the overdue payment amount, the steps to be taken to address the issue, and the consequences of non-payment.3. Corporate Financing and Ownership: A company can be issued a notice of deficiency if it fails to comply with certain regulations related to its finances or ownership structure. For example, a publicly traded company is obligated to maintain a certain amount of shareholder’s equity to remain listed on a stock exchange. If a company’s shareholder’s equity falls below the minimum threshold, the exchange may issue a notice of deficiency, alerting the company to rectify the situation within a specified time or face potential delisting.

Frequently Asked Questions(FAQ)

What is a Notice of Deficiency?

A Notice of Deficiency is a legal document sent by a tax authority to a taxpayer indicating that the taxpayer owes additional taxes due to inaccuracies or discrepancies in a previously filed tax return.

Who issues a Notice of Deficiency?

Typically, the Internal Revenue Service (IRS) in the United States or similar taxable bodies in other countries issue a Notice of Deficiency.

Can I challenge a Notice of Deficiency?

Yes, a taxpayer has the right to challenge a Notice of Deficiency in tax court before paying the assessed amount.

How long do I have to respond to a Notice of Deficiency?

Usually, a taxpayer has 90 days to respond or petition the tax court after receiving a Notice of Deficiency.

What happens if I ignore a Notice of Deficiency?

If a Notice of Deficiency is ignored, the tax authority will generally assess the tax indicated in the notice and require payment.

How can I avoid receiving a Notice of Deficiency?

The most effective way of not receiving a Notice of Deficiency is to ensure accuracy and completeness in your tax return. If you’re unsure, consider hiring an accountant or use a tax software program.

What should I do once I receive a Notice of Deficiency?

If you receive a Notice of Deficiency, it’s recommended to seek legal advice or speak with a tax professional. They can guide you through the process of challenging the notice or arranging payment, if needed.

Does a Notice of Deficiency apply to both businesses and individuals?

Yes, a Notice of Deficiency can be issued to both individuals and businesses if the tax authority believes there has been an under-reporting of tax liabilities.

Related Finance Terms

  • Tax Audit: An official examination of tax returns by the IRS to verify accuracy.
  • Assessment: The process used by tax authorities to calculate the tax owed by a taxpayer.
  • Tax Code: Formal regulations set by a government about how taxes should be paid.
  • IRS (Internal Revenue Service): U.S. government agency responsible for tax collection and tax law enforcement.
  • Appeals Process: The procedure taxpayers can follow if they disagree with a decision made by tax authorities.

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