Got an IRS Notice? Learn the Top Codes

Chad Dickinson • May 15, 2025

Getting a letter from the IRS can be nerve-wracking—especially when it’s packed with confusing codes and no clear explanation. But not all IRS notices are bad news, and understanding what the codes mean can help you act faster (and smarter).

Let’s break down the most common IRS notice codes you’re likely to see—and what they’re really telling you.

Why You Got a Letter from the IRS

The IRS sends letters for a few main reasons:

You owe taxes or missed a payment
You didn’t file a return (or there’s a problem with what you filed)
You’re due a refund or adjustment
They need more information to process your return
There’s a suspected identity issue

Each letter includes a notice number, usually in the upper right-hand corner (example: CP14, LT11, 5071C, etc.). That code tells you what the letter is about.

Top IRS Notice Codes You Should Know

CP14 – Balance Due Notice

This is the most common IRS notice. It means you owe money—whether it’s from an underpayment, late filing, or adjustment. It’s the IRS’s way of saying, “We see a problem. Pay up.”

CP501 or CP503 – Reminder You Still Owe

If you ignore the CP14, you’ll likely get one of these next. They’re follow-up notices reminding you of your unpaid balance and potential penalties.

LT11 or CP504 – Final Notice Before Levy

This is the serious one. It means the IRS is about to take action—like garnishing wages or levying bank accounts—if you don’t respond. Time to get professional help.

5071C – Identity Verification Needed

The IRS needs to confirm you actually filed your return. Until you verify your identity online or by phone, they won’t process your return or issue a refund.

CP2000 – Unreported Income

This notice means the income on your tax return doesn’t match what third parties (like banks or employers) reported to the IRS. It often results in a proposed tax adjustment.

Need More? Here’s the Full List from the IRS

Want to see every IRS notice code and its meaning? Check out the official IRS reference page:
IRS Notices and Letters – What They Mean

What to Do If You Get a Letter

Don’t ignore it. Even if you’re scared or confused.
Read it carefully. Note deadlines, amounts owed, and next steps.
Respond promptly. Many notices can be resolved simply if you act quickly.
Call us if you’re unsure. At Arch Tax, we can decode the letter and help you take the right next step.