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CP518B

CP518B: Final reminder to file a business tax return

Prepared by TaxRZR editorial team · IRS sources checked 2026-10-29 (ET) · professional review pending · This page’s Source Notes

CP518B is a final reminder that the IRS still has no record of prior business tax returns. Match the business name, EIN, return type and tax periods before responding. “Final reminder” concerns filing compliance; it is not a final notice of intent to levy or a new CDP hearing opportunity.

Notice scope. For a business missing-return notice bearing the full B-suffix code. Match the business name, employer identification number (EIN), return type and tax period on the actual notice. This is not individual CP59, CP515 or CP518 guidance. Book chapters offer general recordkeeping and business context, not verified instructions for a particular business return.
Notice-specific source status. IRS CP518B business notice page checked October 29, 2026. Its business response section and FAQ conflict on recently filed returns: four weeks with the same name/EIN versus eight weeks, and the FAQ refers to a Social Security number. This page flags that inconsistency rather than treating either period as a universal safe harbor. Professional review pending. Confirm unclear instructions with the IRS number on your notice.

What the IRS can do next

If the IRS does not hear from you, it may determine your tax for you; penalties and interest can continue to accrue. Refunds for the current or a prior tax year may be delayed because of the unfiled return. Do not wait for another reminder, and do not assume this filing notice postpones action on other liabilities.

Respond promptly by any date printed on your CP518B. Processing windows are not response deadlines or hearing periods.

The business instructions say you may disregard CP518B if you filed within the last four weeks using the same name and EIN. They ask for an explanation if you already filed and more than four weeks have passed, or filed under a different name or EIN. However, the same page’s FAQ says no action is needed within eight weeks. Because these conflict, do not rely on the eight-week FAQ to ignore your business notice; follow the printed instructions and call its IRS number if unsure. File even if you cannot pay in full.

Next step

Check whether the business return was accepted under the name and EIN on the notice. Send the signed paper return and enclosed Response form as directed, or clarify the conflicting recent-filing instructions with the IRS before deciding not to respond.

Steps to work through

  1. 01Identify the missing return type and tax period, and match the business name and EIN. An attempted e-file is not proof of acceptance.
  2. 02If required and unfiled, send a signed paper tax return with all required schedules. Complete the enclosed Response form to explain the reason for filing late.
  3. 03Use the enclosed Response form to explain why you believe no return is required, that you already filed and more than four weeks have passed, or that you filed under a different name or EIN. For a recently filed return, check the conflicting processing guidance above rather than assuming a blanket waiting period.
  4. 04The verified CP518B page says to use the enclosed envelope or fax documents to 855-800-5944. Follow your actual notice if different and confirm any uncertainty with its IRS number. If using an online fax service, review its privacy and security policies before sending tax information.
  5. 05Keep copies and proof of delivery. If you disagree, call the toll-free number on your notice with records ready. If you cannot pay in full, ask separately about payment options; inability to pay does not remove a filing requirement.

Common misreadings

  • Use the enclosed business Response form, not an assumed individual Form 15103 procedure. A response explanation does not replace a required return.
  • The four-week business instructions and eight-week FAQ conflict. Neither is a new response deadline, and filing under a different EIN or name needs attention.
  • Do not interpret “final reminder” as a CDP final levy notice, a Tax Court petition window, or proof that earlier reminders had to be sent.

Read in the book

Official sources

Source status. Based on our draft book dated October 29, 2026, with IRS sources checked October 29, 2026. Professional review pending. General federal tax education, not individual tax or legal advice. Your actual notice and current IRS instructions control.
Scope. These pages cover federal IRS notices, not state tax agency notices. A federal levy of a state refund is not state-specific tax guidance. The collection ladder is an illustration, not a required sequence or a promise that another warning will arrive.