IRS Letter 531
Notice of Deficiency — 90-Day Letter
You have 90 days to file a Tax Court petition — or the IRS's assessment becomes final.
Deadline
90 days (150 days if addressed to a person outside the US) from notice date to file Tax Court petition
The 90-day deadline is jurisdictional — if you miss it, you permanently lose the right to challenge the assessment in Tax Court, and the deficiency is automatically assessed.
Act within days — enforcement is imminent or already in progress.
What IRS Letter 531 Means
Letter 531 — commonly called the 90-Day Letter or Notice of Deficiency — is one of the most important and time-sensitive documents the IRS sends. It represents the end of the examination or underreporter process and the IRS's final proposed assessment before it becomes legally binding.
This letter gives you 90 days to petition the U.S. Tax Court for a redetermination of the deficiency. During this 90-day window, the IRS cannot assess or collect the proposed amount. If you file a Tax Court petition, assessment is further delayed while your case is litigated.
If the 90-day deadline passes without a petition, the IRS automatically assesses the full deficiency plus penalties. You can still pay the tax and then file a refund claim, but the Tax Court route — which allows you to fight the IRS without paying first — is permanently closed.
What the IRS Can Do If You Don't Respond
- Automatically assess the full proposed deficiency plus penalties after 90 days
- Begin collection on the assessed amount including levy and lien action
- Impose accuracy-related penalties of 20% of the underpayment
- Add interest from the original due date of the return
What You Should Do Right Now
- 1
Calendar the 90-day deadline immediately — it is jurisdictional and cannot be extended
- 2
Contact a tax professional within the first week — building a Tax Court case takes time
- 3
Evaluate whether the IRS's position is correct — many deficiencies contain errors or omissions
- 4
If you agree with the proposed assessment, you can sign the waiver and pay without filing in Tax Court
- 5
If you partially agree, a Tax Court petition still allows for settlement negotiation
Resolution Options Available to You
File a petition within 90 days to formally challenge the deficiency
Even before Tax Court, the IRS Appeals Office can resolve many deficiencies
Professional representation throughout the examination process
Challenge accuracy-related penalties with reasonable cause
Frequently Asked Questions About IRS Letter 531
What happens if I miss the 90-day Tax Court deadline?
The IRS automatically assesses the full proposed tax, penalties, and interest. You permanently lose the right to challenge in Tax Court without paying first. You can still pay and file a refund claim, but the burden of proof shifts to you in a different forum.
Does filing in Tax Court mean I have to go to trial?
No. The vast majority of Tax Court cases — over 85% — settle before trial. Filing the petition opens negotiation with IRS counsel and gives you access to the administrative settlement process.
Can I go to Tax Court without a lawyer?
Taxpayers can represent themselves (pro se) in Tax Court. However, for anything other than a small case (under $50,000), professional representation is strongly recommended.
What is the difference between a 30-Day Letter and a 90-Day Letter?
The 30-Day Letter (Letter 525) is the IRS's proposed audit adjustment — you can still appeal internally. The 90-Day Letter (Letter 531) is the final step — your only option is Tax Court or acceptance.
Professional References
IRC: IRC §6212 — Notice of Deficiency; IRC §6213 — Restrictions on Assessment
IRM: IRM 4.8.9 — Statutory Notices of Deficiency
Got IRS Letter 531? Let's Resolve It.
ebotCPA represents taxpayers in Irving, Dallas, Fort Worth, and across Texas. Free consultation — no obligation.