On the paper
Read whether the notice asks for money, for a return, or for both, and note which tax years it names for each request.
Count the tax years. LT16 is one of the few notices that mixes a filing problem with a payment problem in the same letter, and the years listed for the missing return are often not the years carrying the balance. Writing both lists down before you call is the difference between one call and three.
Find the date printed on your notice or letter. The paper notice and the current official IRS instructions control, even where this page differs.
Where this notice comes from
LT16 comes from the automated collection system rather than from an assigned revenue officer. It is a request to make contact, and the phone number on it routes to the unit holding the account.
A file with both an unfiled return and an unpaid balance cannot usually be resolved in one step, because the IRS generally requires filing compliance before it approves a collection alternative. The filing side has to move first.
If the missing return would produce a refund, the Internal Revenue Code sets time limits on claiming it. A year left unfiled long enough stops being a refund and becomes a balance the taxpayer cannot recover.
General next steps
- Separate the notice into two lists: years with a balance, and years with a return the IRS says it has not received.
- File anything missing, or be ready to explain why no return was required for that year.
- Call the number on the notice with both lists in front of you and record the date and the name of the person you speak with.
Timing
The IRS page for LT16, checked September 10, 2026, gives no general period and says the specific instructions and dates are on the notice itself. The date printed on the notice controls; do not calculate a deadline from this page.
What LT16 does not mean
LT16 does not mean the IRS has prepared a substitute return for the missing year, and it does not mean a levy is imminent. It also does not mean the two problems it names are connected. A return can be missing for a year that carries no balance at all.
What this page cannot tell you
This page cannot tell you whether a return was required for a given year or what the IRS will accept as an explanation.
How do I respond to an IRS collection notice?
Read the paper notice first. Identify the letter code, the assessed balance, and any date printed on it. Read How do I respond to an IRS collection notice?.
IRS collections
This letter involves an unpaid IRS balance or a collection action. Read IRS collections.
Official sources
If anything on this page differs from your notice or from current IRS instructions, follow the notice and the IRS.
Common questions
The notice says a return is missing, but I filed it.
Find the proof of filing: the acceptance record from electronic filing, or the certified mail receipt. The IRS unit on the notice can locate a return that posted to the wrong year or was never processed, and the proof is what moves that conversation.
Should I file the missing return before calling?
Filing compliance is generally a precondition to a collection alternative, so a completed return strengthens the call. If the return cannot be completed quickly, the call can still establish contact and identify what the IRS is looking for.
What enforcement action does the notice mean?
The IRS names a federal tax lien and seizure of assets or wages as possibilities on this page. Those steps have their own notice requirements, and a levy on wages or a bank account requires a later final notice with hearing rights.