IRS Notice Codes — What CP01-CP504 Mean and What to Do
Complete guide to IRS notice codes CP01, CP14, CP501, CP2000 and more. What each letter means, response deadlines, payment plans, scams to avoid.
IRS Notice Codes Guide
Every IRS letter has a code (CP## or Letter ####) that tells you what it means and what to do.
Notice codes covered
- CP01 — IRS CP01 Notice — Identity Theft Alert
- CP14 — IRS CP14 — Balance Due Notice (You Owe Taxes)
- CP2000 — IRS CP2000 — Underreporter Notice (Income Mismatch)
- CP501 — IRS CP501 — Reminder Notice (Balance Owed)
- CP14H — IRS CP14H — Shared Responsibility Payment Notice (ACA)
- Letter5821 — IRS Letter 5821 — Your ITIN Has Expired
Last verified: 2026-05-25.
General procedural information for educational purposes. Not legal, tax, or immigration advice. Laws and fees change — verify with the issuing agency before taking action. For case-specific guidance, consult a licensed immigration attorney or other appropriate professional.
Related procedural information
- ITIN — file taxes without SSN — required for federal and most state filings without SSN
- ITIN-friendly business banking — for self-employment and freelance income
- Form an LLC to structure your business income — pass-through tax treatment for ITIN holders
- State driver’s license requirements (DMV) — license status affects residency for state tax
- Find a CPA or enrolled agent — for cross-border or treaty filings
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IRS CP01 Notice — Identity Theft Alert
IRS CP01 is sent when IRS suspects identity theft on your tax return. They've locked your account. Must verify your identity to process refund.
IRS CP14 — Balance Due Notice (You Owe Taxes)
IRS CP14 says you owe taxes from your filed return. Includes amount + due date. Pay by deadline or interest/penalties accrue.
IRS CP14H — Shared Responsibility Payment Notice (ACA)
IRS CP14H is for unpaid Affordable Care Act Shared Responsibility Payment (ACA insurance penalty). May affect ITIN holders who didn't have coverage.
IRS CP2000 — Underreporter Notice (Income Mismatch)
IRS CP2000 means IRS found income on W-2/1099 not reported on your return. Proposes adjustment. RESPOND within 30 days agreeing or disagreeing.
IRS CP501 — Reminder Notice (Balance Owed)
IRS CP501 is first reminder that you owe taxes after CP14 was ignored. Still time to pay before more aggressive collection.
IRS Letter 5821 — Your ITIN Has Expired
IRS Letter 5821 informs your ITIN expired (not used in 3 consecutive tax years). You need to renew before filing next return.
General information, not legal advice. MigrantUSA is an independent publisher and is not a law firm; using this site does not create an attorney-client relationship, and this content is not a substitute for advice from a licensed attorney about your specific situation. US federal, state, and local government procedures, fees, and forms change. Always verify current details directly with the relevant agency before acting. For immigration, tax, or other legal matters specific to your situation, consult a licensed attorney or BIA-accredited representative.