IRS LT18 Notice: Overdue Tax Returns, File Within 10 Days
The IRS hasn't received a response to its earlier requests for overdue tax returns. Send the completed returns to the address on the notice within 10 days.
Numbers covered by this guide
LT18
ST18
Check the identifier and follow the instructions on your own notice.
Published by the Law Offices of Darrin T. Mish, P.A.•Updated February 22, 2026
General information only, not legal advice. Using this page does not create an attorney-client relationship. This information may be incomplete or out of date and is provided without any guarantee; follow the instructions and deadline on your own notice. Full terms and disclaimer
File the overdue returns listed on the notice and send them to the address on the notice within 10 days of the notice date.
Deadline calculator
Estimate your LT18 deadline
Estimate only. If your notice shows a specific respond-by date, that date controls. Some deadlines run from the mailing date, and a statewide holiday where the IRS office is located can also extend a deadline. Mail early, keep proof of mailing, and if a deadline matters, have a professional confirm it. Terms and disclaimer
See it explained
LT18 in plain English
LT18: what it means, in 30 secondsA 30-second overview from tax attorney Darrin T. Mish: what this notice is, the deadline, and your first move.
What This Notice Means
The IRS has asked you before to file overdue tax returns, and it hasn't heard back. LT18 is the follow-up. The notice lists the returns the IRS says are missing. These can include business returns, such as employment tax returns.
LT18 is not a payment plan notice. It is about returns that haven't been filed.
What to Do
Read the notice and identify each return and tax period listed.
Complete the missing returns and send them to the address on the notice within 10 days of the notice date.
Keep copies of every return you send and proof of mailing.
If You Already Filed
If it's been more than 10 weeks since you sent the return, send the IRS a signed copy of it again.
If You Had No Employees
If the notice asks for employment tax returns for a period when you had no employees, call the number on the notice and tell the IRS.
If You Can't Pay What the Returns Show
File anyway. Not filing doesn't make the tax go away, and the filing problem is separate from the payment problem. Once the returns are in, you can ask about a payment plan for any balance.
Why It Matters
The IRS has already asked more than once. Answering now, with the returns themselves, is the simplest way to close the request. If you can't get the returns done in 10 days, call the number on the notice before the deadline and explain where things stand.
You can authorize a representative to deal with the IRS for you with Form 2848.
If you received an LT18 and need help getting overdue returns filed, call us at (813) 229-7100.
This letter has a clock on it. Don’t run it out alone.
Free consultation with Darrin T. Mish, a Tampa tax attorney licensed since 1993 and admitted to the U.S. Tax Court. Bring the letter.