IRS notices explained: what every letter number actually means.

IRS Notices · 9 min read

Notices that say "we think you owe more"

CP2000 — Underreported income notice. The most common notice we see. It means the income on your tax return doesn't match what a third party (an employer, bank, brokerage, crypto exchange) reported to the IRS. It is not an audit and it is not a bill — it's a proposal. You can agree, partially agree, or dispute it with documentation. A lot of CP2000 notices are wrong or overstated because they don't account for basis, deductions, or a form you simply forgot to include.

Notice of Individual Income Tax Adjustment. Similar concept at the state level — the state has adjusted your reported income or credits based on data they have. Read exactly what changed before assuming it's correct.

Notices about balances due — the escalation ladder

The IRS collection process follows a predictable sequence, and each notice raises the stakes:

• CP14 — First bill after a balance is assessed. Routine, but the clock on penalties and interest starts here.
• CP501 / CP502 — Reminder notices that a balance is still unpaid.
• CP503 — Second reminder. Tone shifts noticeably more urgent. Still time to act without enforcement action.
• CP504 — Notice of intent to levy your state tax refund, and it signals more aggressive collection (bank levies, wage garnishment) is close behind.
• CP90 / CP297 — Final Notice of Intent to Levy, with your right to a Collection Due Process (CDP) hearing. A 30-day, time-sensitive notice. Once it expires, the IRS can legally levy your bank accounts or wages without further notice.

Notices about liens, levies, and enforcement already underway

CP39 — Refund offset notice. The IRS applied your expected refund to a past-due balance on a different account.

9297 (Form 9297, Summary of Taxpayer Contact) — Requests specific financial information, often tied to Form 433-A/433-B. Getting one usually means your case has been assigned to a live Revenue Officer.

ACS Support / "Stop 5050" — IRS Automated Collection System correspondence, meaning your account is in the automated collection queue rather than assigned to a local Revenue Officer.

CP220 / CP21B — Notices reflecting a change the IRS made to your account.

Notice 1462 — Generally relates to identity verification or a hold on your return/refund pending confirmation.

Notices specific to business and payroll tax

CP134B — Discrepancy notice for payroll tax deposits (Form 941), where what you reported doesn't match IRS records. Read the full CP134B guide →

CP081B — Notice regarding a credit or return that appears missing from your account. Read the full CP081B guide →

CP140 — Your overdue account was assigned to a private collection agency. Read the full CP140 guide →

The one thing every notice has in common

Every one of these has a deadline, usually 30 days from the notice date. None of them get better by waiting — penalties and interest accrue daily, and each unanswered notice tends to trigger the next, more serious one in the sequence.