How to read this page.
Each notice below lists the CP (computer-paragraph) or Letter number the IRS uses, a short description of what the notice actually means, and the most important deadline associated with it. This is reference material — useful for understanding what you received, not a substitute for advice on what to do about it. The $105 Transcript Analysis includes a preliminary review of any active notice against the full transcript picture.
Collection notices
CP14 — Balance Due. The first notice a taxpayer receives when they have a balance due on a return. Usually 30 days to respond. Not an enforcement notice; a demand.
CP501, CP503, CP504 — Reminder series. Successive demand letters after a CP14. CP504 is the last notice before the IRS begins lien filing or levy preparation. Each escalates; none of them should be ignored.
LT11 / Letter 1058 — Final Notice of Intent to Levy. The notice that triggers the 30-day Collection Due Process hearing window. Miss this window and CDP rights are forfeited. One of the most consequential letters in the IRS collection sequence.
LT16 — Please Call Us About Your Account. Soft-contact letter that often precedes enforcement. Worth responding to before it escalates.
CP90 / CP297 — Notice of Levy. Levy notice issued to a third party (employer, bank) directing the levy. By the time this arrives, the CDP window has typically already passed.
CP91 / CP298 — Notice of Levy on Social Security. Levy against Social Security benefits. Specific statutory limits on amounts that can be taken, but the levy itself is in place.
Letter 3172 — Notice of Federal Tax Lien Filing. Triggers a separate 30-day CDP hearing window tied to the lien filing. Different from the levy CDP window.
Examination notices
CP2000 — Notice of Proposed Adjustment. Generated by the IRS automated underreporter program when reported income does not match third-party information returns (W-2s, 1099s). Not a final assessment; a proposal the taxpayer can agree to, partially agree to, or contest. 30-day response window.
Letter 566 / Letter 525 — Audit notification. Initiates an examination. Specifies items under review and requests documentation. This is the point at which audit strategy matters most — the administrative record being built here will determine what happens at Appeals and, if it goes further, at Tax Court.
Letter 950 — 30-Day Letter. Issued at the close of an examination that resulted in proposed adjustments the taxpayer disagrees with. 30 days to file a formal written protest to IRS Appeals.
Letter 3219 / CP3219A — Statutory Notice of Deficiency ("90-Day Letter"). The single most time-sensitive notice the IRS issues. 90 days from the date on the notice to file a petition with the United States Tax Court (150 days if addressed to a person outside the United States). Miss the deadline and Tax Court jurisdiction is permanently foreclosed; the deficiency becomes assessed and the only recourse is to pay and sue for refund in district court. There are no extensions.
Appeals and enforcement
Letter 4837 — Appeals Acknowledgment. Confirms a protest has been received and assigned. The first step in the Appeals process.
Letter 1153 — Trust Fund Recovery Penalty Proposed Assessment. Begins the process of personally assessing unpaid employment trust fund taxes against "responsible persons." 60-day response window. TFRP defense turns heavily on what is argued and documented at this stage.
Letter 2205 — Examination interview appointment. Scheduling letter for an in-person IRS examination interview. Counsel is typically advised before this interview.
Letter 915 — Examination Report. Transmits the examiner's findings. Taxpayer has 30 days to respond or it proceeds to the 30-day letter and then Appeals.
Identity and compliance
CP2005 / CP2006 — Inquiry closed. The IRS has accepted the taxpayer's response and closed the inquiry without further action.
Letter 4883C / 5071C / 5447C — Identity verification. Sent when the IRS needs to verify the taxpayer's identity before processing a return or issuing a refund. These letters are sometimes mimicked by scammers; verification should always go through the official IRS phone number or in-person process listed in the letter.