LT16 — Please File Your Tax Returns: Why the IRS Sends This Notice, the Substitute for Return (SFR) Process, Failure-to-File Penalties, and the Correct Response Strategy for Non-Filers in 2026
LT16 is the IRS's notice to taxpayers who have one or more unfiled tax returns. The notice requests that the taxpayer file the missing returns or explain why they are not required to file. LT16 is typically sent after the IRS has identified income reported by third parties (W-2s, 1099s) that does not match a filed return — the IRS knows the taxpayer received income but has not filed. If the taxpayer does not respond to LT16, the IRS will prepare a Substitute for Return (SFR) under IRC §6020(b) — a return prepared by the IRS using only the income information it has, with no deductions, no credits, and no exemptions beyond the standard deduction. The SFR almost always results in a significantly higher tax liability than a properly prepared return. This guide covers the LT16 response strategy, the SFR process, the failure-to-file and failure-to-pay penalties, and the voluntary disclosure procedures for non-filers.
LT16 Response Strategy: Step by Step
- Gather all income documents: Obtain all W-2s, 1099s, K-1s, and other income documents for each unfiled year. The IRS has this information already — the goal is to prepare a return that claims all allowable deductions and credits to minimize the tax liability below what the SFR would assess.
- Prepare the returns from the most recent year backward: Start with the most recent unfiled year and work backward. This allows carryforward items (NOLs, capital loss carryforwards, basis) to flow correctly from year to year.
- File all returns before the SFR is assessed: Once the IRS assesses an SFR, the collection process begins. Filing a voluntary return before the SFR replaces the SFR and gives the taxpayer the benefit of all deductions and credits. After SFR assessment, the taxpayer must still file the correct return to replace the SFR, but the assessment has already triggered penalties and interest.
- Request penalty abatement: After filing, request abatement of the failure-to-file and failure-to-pay penalties under the First Time Abatement (FTA) policy or reasonable cause. FTA is available for taxpayers with a clean compliance history for the prior 3 years.
- Arrange payment or installment agreement: If the client cannot pay the full balance, establish an installment agreement or consider an Offer in Compromise if the liability exceeds the client's reasonable collection potential.
Frequently Asked Questions — LT16
File Before the IRS Files for You — The SFR Has No Deductions
A Substitute for Return prepared by the IRS uses only income data — no deductions, no credits, no exemptions beyond the standard deduction. A qualified tax professional can prepare all missing returns, claim every allowable deduction, and minimize the tax liability before the SFR is assessed.
Connect with a Tax ProfessionalReady to Reduce Your Tax Burden?
Our tax advisors specialize in helping professionals and business owners implement these strategies. Book a free strategy call to see how much you could save.
Book A Strategy Call With A Tax AdvisorFrequently Asked Questions
Verify the notice is legitimate by checking the notice number and comparing it to your filed return. Do not ignore it — most IRS notices have strict response deadlines. Pull your IRS account transcript online at IRS.gov to confirm the assessment matches what the IRS shows on file.
Most IRS notices require a response within 30 days from the date printed on the notice. Some notices, like statutory notices of deficiency, give you 90 days. Missing the deadline can result in default assessments, loss of appeal rights, or escalation to collection action including liens and levies.
Yes. First-time penalty abatement (FTA) is available if you have a clean three-year compliance history — meaning you filed all required returns on time and paid all taxes due for the prior three years. You can request FTA by calling the IRS at 1-800-829-4933 or by submitting a written request.
You have the right to dispute any IRS assessment. File a written protest within the response window explaining why you disagree, attach supporting documentation, and request a conference with IRS Appeals. If the amount is under $25,000, you can use the simplified Collection Due Process (CDP) hearing request.
Yes. The IRS offers installment agreements for taxpayers who cannot pay in full. For balances under $50,000, you can apply online at IRS.gov/OPA. For larger balances, you will need to submit Form 9465 along with Form 433-A (Collection Information Statement) documenting your income and expenses.
An IRS notice alone does not affect your credit score. However, if the balance remains unpaid and the IRS files a federal tax lien (Notice of Federal Tax Lien), that lien becomes a public record and can significantly damage your credit. Paying or resolving the balance before lien filing protects your credit.
For simple issues like verifying a payment or correcting a minor discrepancy, calling 1-800-829-4933 is faster. For complex disputes, penalty abatement requests, or anything involving legal arguments, always respond in writing via certified mail with return receipt so you have proof of timely response.
Yes. Your CPA, EA, or tax attorney can represent you before the IRS using Form 2848 (Power of Attorney). Once filed, the IRS will communicate directly with your representative. This is strongly recommended for notices involving audits, large balances, or potential criminal referrals.
Ignoring an IRS notice triggers an escalation sequence: the IRS will send follow-up notices (CP501, CP503, CP504), then a final notice of intent to levy (LT11 or CP90). After the final notice, the IRS can levy bank accounts, garnish wages, and seize property without further warning.
Yes. The IRS generally has 10 years from the date of assessment to collect a tax debt (the Collection Statute Expiration Date or CSED). After 10 years, the debt expires and the IRS can no longer collect. However, certain actions — like filing an Offer in Compromise or requesting a CDP hearing — can toll (pause) the statute.
Penalties can be abated through FTA, reasonable cause, or statutory exception. Interest, however, is almost never abated — the IRS is required by law to charge interest on unpaid tax from the due date until the date of payment. The only way to stop interest from accruing is to pay the underlying tax balance.