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IRS CP518 Notice Explained: Final Reminder to File Your Return

By Andrew Nocera, Tax Preparer & Small-Business Finance Consultant, Enhance Finance LLC (serving all of Connecticut from Shelton). Updated November 2026.

A CP518 is the IRS's final reminder that it still has no record of a prior-year tax return from you. It often follows a CP59. Respond right away: file the return, or explain why you didn't have to.

IRSWe can help with this
What it isFinal reminder: no record of your prior-year return.
Deadline"Immediately respond to the notice."
Official pageIRS: Understanding your CP518 notice
On this page
  1. What the CP518 is
  2. Why you got it
  3. Deadline
  4. What to do, step by step
  5. Common mistakes
  6. When to get help
  7. FAQ

What the CP518 is

The IRS says: "This is your final reminder; we still don't have a record that you filed your prior year tax returns." The IRS forms it points to (Form 15103, Form 1040 Return Delinquency) show it's about a personal Form 1040 return. If you got a CP59 earlier about the same year, this is the follow-up. (See the CP59 summary.)

Why you got it

  • You didn't file a return for that year.
  • You filed, but the return was rejected, or the name, Social Security number or year doesn't match what the IRS has.
  • You filed recently and it hasn't been processed yet. The IRS says you don't have to do anything if you filed within the last 8 weeks.
  • You weren't required to file.

Deadline

In the IRS's words: "Immediately respond to the notice." If the IRS doesn't hear from you, it says: "We may determine your tax for you," "Penalty and interest may continue to accrue," and "If you are owed a refund, it may be delayed because of this unfiled return."
Is it real? The IRS says it normally contacts you the first time by U.S. mail, and a social media direct message is never from the IRS. If you aren't sure a letter is genuine, check it against your IRS Online Account or IRS: How to know it's really the IRS before you call any number or pay anything. More warning signs: scam checklist.

What to do, step by step

  1. Check the details on the notice: name, Social Security number and tax year.
  2. Filed within the last 8 weeks? The IRS says you don't have to do anything.
  3. Didn't file, or filed more than 8 weeks ago? Complete Form 15103, Form 1040 Return Delinquency and send a signed, dated copy of the return with it. Form 15103 is where you explain why you're filing late, or that you already filed.
  4. Not required to file? Use Form 15103 to explain why. The IRS says if you're only sending Form 15103 for that reason, you can submit it online through an IRS Online Account.
  5. Send it the way the notice says: to the address on the notice, or by fax to the number on the notice.
  6. Owe money? File anyway. The IRS says you can request a payment plan to pay your balance over time (IRS: Payment plans).
  7. Check your withholding so the same gap doesn't happen again. The IRS points to its Tax Withholding Estimator.

The IRS accepts returns electronically for the 2 most recent prior years, but you need an e-file provider that offers it.

Common mistakes

  • Waiting until you can pay. File now and ask for a payment plan for what you owe.
  • Sending a return without Form 15103.
  • Mismatched details between the return and the notice (name, SSN, year).
  • Assuming an old e-file went through. Check whether it was rejected.
  • Ignoring it because you think you're owed a refund. The IRS sets time limits on claiming refunds and credits.

When to get help

Get help if you're missing more than one year, you don't have your W-2s or 1099s, or you're not sure whether you had to file. We can help you pull together your income records, prepare the late return and Form 15103, and request a payment plan if you owe. If the IRS has already determined your tax for you or started collection, consider an enrolled agent, CPA or attorney.

We can help with this. We can help you understand the letter, gather your documents, and prepare your response or payment plan request. Book a 30-minute call or see all booking options.

General information, not advice for your situation. Not tax, legal, investment, or insurance advice. Agency rules and procedures change; always follow the instructions and dates on your own notice and check the official sources below.

Frequently asked questions

What is the difference between a CP59 and a CP518?

Both say the IRS has no record of your prior-year return. The IRS calls the CP518 your final reminder, so it often comes after a CP59 that was not answered.

I just filed my return. Do I need to do anything?

The IRS says you do not have to do anything if you filed your tax return within the last 8 weeks.

What is Form 15103?

Form 15103, Form 1040 Return Delinquency, is the IRS form you send with a late return to explain why it is late or that you already filed, or on its own to explain why you did not have to file.

What if I cannot pay what I owe?

File the return anyway. The IRS says you can request a payment plan to pay your balance over time.

What happens if I ignore a CP518?

The IRS says it may determine your tax for you, penalties and interest may continue to accrue, and any refund you are owed may be delayed.

Sources (checked November 10, 2026)

  • IRS, Understanding your CP518 notice (final reminder, respond immediately, Form 15103, 8-week rule, e-file for 2 prior years, consequences): www.irs.gov
  • IRS, Understanding your CP59 notice: www.irs.gov
  • IRS, Form 15103, Form 1040 Return Delinquency: www.irs.gov
  • IRS, Payment plans (installment agreements): www.irs.gov

Behind on a return? Get it filed and the CP518 answered with a Connecticut tax preparer.

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