IRS NOTICE REFERENCE
Understanding your LT51 notice
We're trying to collect unfiled tax returns or your Shared Responsibility Payment (SRP). We previously notified you that we would contact third parties to get or verify your contact information. We’ll continue to contact…
General information only. Not legal or tax advice.
Notice details
- Notice code
- LT51
- Category
- Filing and non-filer
- Severity tier
- Tier 2 — Action or response expected. The IRS has taken or proposed an action and expects a response or payment.
- Governing law
- §6651; §6012 (Internal Revenue Code sections)
- Source
- IRS.gov — Understanding Your IRS Notice
What this notice is
We're trying to collect unfiled tax returns or your Shared Responsibility Payment (SRP). We previously notified you that we would contact third parties to get or verify your contact information. We’ll continue to contact others through the period shown on your notice.
Source: IRS.gov. Reproduced for reference. General information — not legal or tax advice.
What the IRS says to do
File all missing tax return(s) . Mail your tax return(s) and supporting documentation to the address at the top of your notice by the date shown on your notice. See “Filing my missing returns” for more information on how to file your return below. Pay your balance in full by the date shown on your notice to avoid paying more in penalties and interest. If you can't pay your balance in full, learn more about applying for a payment plan online . If you're experiencing financial hardship, learn about other options like temporarily delaying collection or settling your tax debt with the IRS. See your Online Account to access your account information, request a transcript, or view payment history.
This is the IRS’s own guidance reproduced from the IRS notice page. It describes the IRS’s process — it is not legal or tax advice from TaxRiskOS.
Governing IRS procedure (Internal Revenue Manual)
The IRS’s own internal procedures for handling this notice type are documented in the Internal Revenue Manual:
- IRM 5.1.11 — 5.1.11 Delinquent Return Investigations
- IRM 5.18.1 — 5.18.1 Automated Substitute for Return (ASFR) Program
- IRM 4.12.1 — 4.12.1 Nonfiled Returns
Reference to published IRS procedure. General information — not legal or tax advice.
Official IRS reference
Read the official notice page on IRS.gov: https://www.irs.gov/individuals/understanding-your-lt51-notice
Related tools
TaxRiskOS is workflow software for practitioners — it captures the notice, computes the deadline, surfaces the escalation tier, and builds a document checklist. It documents process; it does not give advice or draft responses.
Check this notice’s deadline (free tool)