IRS NOTICE REFERENCE
Understanding your CP400 and CP401 notice
If you receive a CP400 (individuals) or CP401 (businesses) letter, it explains that your case has been received in Appeals. The letter states that you can expect to be contacted within 45 or 60 days, depending on your ty…
General information only. Not legal or tax advice.
Notice details
- Notice code
- CP400-AND-CP401
- Category
- Appeals and collection due process
- Severity tier
- Tier 2 — Action or response expected. The IRS has taken or proposed an action and expects a response or payment.
- Governing law
- §6330; §6331 (Internal Revenue Code sections)
- Source
- IRS.gov — Understanding Your IRS Notice
What this notice is
If you receive a CP400 (individuals) or CP401 (businesses) letter, it explains that your case has been received in Appeals. The letter states that you can expect to be contacted within 45 or 60 days, depending on your type of case.
Source: IRS.gov. Reproduced for reference. General information — not legal or tax advice.
Governing IRS procedure (Internal Revenue Manual)
The IRS’s own internal procedures for handling this notice type are documented in the Internal Revenue Manual:
- IRM 5.1.9 — 5.1.9 Collection Appeal Rights
- IRM 5.19.8 — 5.19.8 Collection Appeal Rights
- IRM 5.12.6 — 5.12.6 Appeals Processes Involving Liens
Reference to published IRS procedure. General information — not legal or tax advice.
Official IRS reference
Read the official notice page on IRS.gov: https://www.irs.gov/individuals/understanding-your-cp400-and-cp401-notice
Related tools
TaxRiskOS is workflow software for practitioners — it captures the notice, computes the deadline, surfaces the escalation tier, and builds a document checklist. It documents process; it does not give advice or draft responses.
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