IRS Notices

IRS CP518 Notice: The Final Unfiled Return Notice, Explained (2026)

By Angeline Balsitis, EA · Reviewed by Melissa Ly, Chief Tax Officer · Updated April 28, 2026 · Editorial Standards

Why you got a CP518

The IRS has income records — W-2s, 1099s, and other forms — showing you likely had a filing requirement for a tax year, but its system shows no return was filed. The CP518 is the last in a short series of reminders. It usually follows a CP59 (first notice) and a CP516 (reminder). By the time the CP518 lands, the automated system is nearly out of patience (the IRS explains it on its Understanding Your CP518 Notice page).

One important thing a CP518 is not: a bill. There's no dollar amount yet because you haven't filed. It's a request for a missing return — and that's actually good news, because it means you still get to file your own numbers before the IRS guesses for you.

What happens if you ignore the CP518

This is where unfiled returns get expensive. The IRS won't simply forget. If you don't respond, the automated process moves forward step by step:

1. CP518 — final reminder. You are here. No tax assessed yet.
2. Substitute for Return (SFR) — the IRS prepares a return for you using only reported income. No deductions, no credits, no dependents, filing status set to single or married-filing-separately. The balance is almost always inflated.
3. CP3219N / Notice of Deficiency — the "90-day letter." You have 90 days to file your own return or petition Tax Court before the tax becomes final.
4. CP14 and the collection sequence — once the SFR tax is assessed, it becomes a balance due. From there the standard order of IRS collection letters kicks in: reminders, a Notice of Intent to Levy, then liens and levies.

In 2026 this matters more than ever. IRS staffing is down, but the notices, SFRs, and levies are issued by automated systems that didn't get cut. The machine keeps moving whether or not a person ever opens your file.

Why filing your own return beats an SFR — a worked example

Say the IRS sees $70,000 of 1099 income for one year. On a Substitute for Return, the IRS taxes the full $70,000 as if it were pure profit — no business expenses, no standard deduction, single filing status. That can produce a tax bill of well over $15,000 before penalties.

Now say you file your own Schedule C showing $30,000 of legitimate business expenses and claim the standard deduction. Your taxable income drops sharply, and the real tax owed might be a few thousand dollars instead. Same income — very different bill. Filing your own return is almost always the single biggest thing you can do to lower what you owe.

First: make sure the CP518 is actually right

A meaningful share of these notices are for years you already filed. Before doing anything else, take ten minutes to check:

• Log into your IRS online account and look at your account transcript for that year. It will show whether a return posted.
• Confirm you even had a filing requirement. If your income was below the filing threshold, you may not have needed to file — but you still need to tell the IRS that.
• Screen for scams. A real CP518 arrives by postal mail, never by email or text. The IRS never demands payment by gift card, wire transfer, or payment app. If you're unsure, our guide on what a certified letter from the IRS means can help you tell real from fake.

If you already filed, send a signed copy of the return with proof of filing — and don't file it a second time.

Your options once you confirm a return is missing

The notice frames this as "file now." In reality there's a smart order to do it in, and several ways to handle the tax once you file:

• File the missing return(s). This is step one no matter what. The IRS generally wants the last six years filed to consider you in good standing. See the IRS guidance on filing past due tax returns.
• Payment plan. If you owe once you file, a monthly installment agreement spreads it out. Balances under about $50,000 often qualify for a streamlined plan without detailed financial disclosure.
• Currently Not Collectible status. If paying anything would create real hardship, collection can be paused while your situation improves.
• Offer in Compromise. Settling for less than the full balance is real, but only when your assets and income genuinely can't cover the debt. An experienced tax professional can tell you if you're a candidate before you spend anything pursuing it.
• Penalty relief. First-time penalty abatement may remove the failure-to-file penalty if this is your first slip in years. Reasonable-cause relief may apply for illness, disaster, or other events beyond your control.

How to respond to a CP518, step by step

1. Pull your transcripts. Check your IRS online account to confirm exactly which year(s) are missing and what income the IRS has on file.
2. Gather your records. W-2s, 1099s, expense receipts, prior returns. The income the IRS has is your floor; your deductions bring the number down.
3. Prepare and file the missing return(s) before the notice deadline — even if you can't pay. Filing stops the Substitute for Return.
4. Respond to the notice. If you had no filing requirement, or already filed, mail back the response section with documentation. Keep copies of everything.
5. Set up a plan for any balance. Pick the option above that fits your finances, or get a professional review first — the order you fix things in (file, abate penalties, then resolve the balance) changes what you end up paying.

CP518 questions, answered

This guide is general information, not tax or legal advice for your specific situation. Eligibility for IRS programs depends on individual facts and circumstances; no outcome is guaranteed.

Related: once an SFR balance is assessed you'll get a CP14 first-bill notice. Not sure where you are in the sequence? See the order of IRS collection letters — or browse all guides.