IRS NOTICE REFERENCE
Understanding Your CP518 Business notice
This is a final reminder notice that we still have no record that you filed your prior tax returns.
General information only. Not legal or tax advice.
Notice details
- Notice code
- CP518-BUSINESS
- Category
- Filing and non-filer
- Severity tier
- Tier 2 — Action or response expected. The IRS has taken or proposed an action and expects a response or payment.
- Governing law
- §6651; §6012 (Internal Revenue Code sections)
- Source
- IRS.gov — Understanding Your IRS Notice
What this notice is
This is a final reminder notice that we still have no record that you filed your prior tax returns.
Source: IRS.gov. Reproduced for reference. General information — not legal or tax advice.
What the IRS says to do
File a paper return with all required schedules using the enclosed envelope or fax your documents to 855-800-5944 using either a fax machine or online fax service. Protect yourself when sending digital data by understanding the fax service’s privacy and security policies. Complete the Response form enclosed with your notice and mail it to us, using the enclosed envelope or fax your documents to 855-800-5944 using either a fax machine or online fax service. Protect yourself when sending digital data by understanding the fax service’s privacy and security policies. Use the response form on your notice to explain: why you're filing late. why you don’t have to file. if you already filed and it's been more than four weeks, or if you used a different name or employer ID number (EIN) than shown on the notice when filing. if you filed within the last four weeks using the same name and EIN shown on the notice, you may disregard this notice. why you're filing late. why you don’t have to file. if you already filed and it's been more than four weeks, or if you used a different name or employer ID number (EIN) than shown on the notice when filing. if you filed within the last four weeks using the same name and EIN shown on the notice, you may disregard this notice.
This is the IRS’s own guidance reproduced from the IRS notice page. It describes the IRS’s process — it is not legal or tax advice from TaxRiskOS.
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 5.1.11 — 5.1.11 Delinquent Return Investigations
- IRM 5.18.1 — 5.18.1 Automated Substitute for Return (ASFR) Program
- IRM 4.12.1 — 4.12.1 Nonfiled Returns
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-cp518-business-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.
Check this notice’s deadline (free tool)