On November 25, 2025, the IRS and President signed the Internal Revenue Service Math and Taxpayer Help Act into law, also known as H.R. 998 or the IRS MATH Act. The Act requires the IRS to give taxpayers clearer, more detailed math error notices and expands the information taxpayers receive when the IRS makes a correction. Here’s a closer look at the IRS Math Act and how you can prepare.

Background- IRS math error notices

Under prior law,  when the IRS made a correction of a mathematical or clerical error on your tax return, they would send a letter saying you made a mistake, sometimes proposing extra taxes owned, but rarely fully explaining the details of your error. As a result, many taxpayers felt confused as to how to fix the problem or why their refund was lower than expected. 

These notices were also often unclear about the taxpayer’s rights. The IRS wasn’t required to fully describe the nature of the error, identify the exact line item that triggered the notice, or even inform taxpayers that they had just 60 days to dispute the change before losing their ability to challenge it in Tax Court. Millions of notices were sent each year, many of which were never received due to lost mail or incomplete information.

What the IRS Math Act means for you

In light of these challenges, the IRS Math Act is designed to make IRS math error notices more clear, fair and easier to remedy.

Under the IRS Math Act, the IRS now has to provide taxpayers with much more detail when it identifies a math or clerical error on a return. This includes:

• Clear Explanation: Every notice must explain the alleged error in plain language, including the nature of the error, the type of error, the applicable Internal Revenue Code section, and the specific tax return line where the issue occurred.
• Show the Math: The IRS must provide a step-by-step breakdown of the calculations that led to their proposed changes—covering adjustments to income, deductions, credits, withholding, NOLs, carryforwards, and more. This means no more mysterious adjustments.
• 60-Day Window to Challenge: Taxpayers  have a full 60 days to dispute the IRS’s math error, and the notice must clearly state this deadline. Previously, missing this window could prevent you from challenging the adjustment at all.
• Better Communication: Notices must be sent to the taxpayer’s last known address and include the phone number for the IRS’s automated transcription service so taxpayers can more easily access information.

Why this matters

Every year, millions of taxpayers get math error notices. Before this law, many taxpayers either didn’t understand the error or weren’t aware they could challenge it, leaving them with extra taxes they didn’t owe, or spending time and money trying to figure it out.

Now, taxpayers have more transparency and a clear path to correct mistakes. For families, small business owners, and retirees alike, this is a meaningful step toward fairness and tax clarity.

The IRS Math and Taxpayer Help Act gives taxpayers more transparency. If the IRS says you made a math error, you’ll get to see the math, understand the issue, and have the opportunity to challenge it.

When is the IRS Math Act effective?

The IRS Math Act is effective one year from its enactment, so November 25, 2026. Even though the IRS is short-staffed and may struggle to meet the one-year deadline, the law still requires them to release instructions within 180 days and start a pilot program within 18 months. More updates will be available with the release of the instructions and pilot program.