How long do I have to respond to IRS Letter 3523?

Tax Court petition due within 90 days (150 if outside the U.S.). Use the deadline printed on your notice and verify how it is calculated. IRS deadlines may run from the notice or mailing date and are not automatically extended because the letter arrived or was opened late.

What should I do if I received IRS Letter 3523?

Decide now whether to petition the U.S. Tax Court by the 'Last Date to Petition Tax Court' shown on the letter. If you are unsure, have a tax professional review the letter before you respond to the IRS.

IRS Letter 3523: Notice of Employment Tax Determination

The IRS says your workers are employees and proposes employment tax. You have 90 days to petition Tax Court (150 if addressed outside the U.S.).

Numbers covered by this guide

Letter 3523
Ltr 3523
Letter 3523-A

Check the identifier and follow the instructions on your own notice.

Published by the Law Offices of Darrin T. Mish, P.A.Updated October 14, 2026

Notice: Letter 3523 / Ltr 3523 / Letter 3523-A
Urgency: Critical
Deadline: Tax Court petition due within 90 days (150 if outside the U.S.)

Your first move

Decide now whether to petition the U.S. Tax Court by the 'Last Date to Petition Tax Court' shown on the letter.

What This Letter Means

Letter 3523, Notice of Employment Tax Determination Under IRC 7436, is your legal notice that you can take the IRS's employment tax decision to the U.S. Tax Court. It follows an employment tax examination where the IRS decided that:

One or more workers you treated as independent contractors are employees, and/or
You don't qualify for relief under Section 530 of the Revenue Act of 1978.

The letter lists the reclassified workers, any employees with additional wage issues, and the proposed employment tax, additions to tax, and penalties for each period. It comes with Form 2504-T (an agreement form), Forms 4666, 4667, and 4668 showing the computations, and Publication 3953, which answers questions about Tax Court. Letter 3523-A is the version issued by the IRS Independent Office of Appeals.

It usually comes after a 30-day letter that went unanswered or a case that didn't settle.

The Deadline

You must file a Tax Court petition before the 91st day after the letter was mailed. If the letter is addressed to you outside the United States, you get 150 days. The letter shows the "Last Date to Petition Tax Court." That deadline is set by law. Calling the IRS, writing to the IRS, or asking for reconsideration does not extend it.

Your Options

Petition Tax Court. Include a copy of the letter and the statements that came with it. Small case procedures may be available when the amount in dispute is $50,000 or less for each calendar quarter.
Agree. Sign and return Form 2504-T. That lets the IRS assess quickly and limits interest.
Do nothing. After the deadline, the IRS assesses the tax, penalties, and interest and bills you. You lose Tax Court. To challenge it later, you generally have to pay the tax for at least one worker for one period, file a refund claim, and sue in District Court or the Court of Federal Claims.

What to Do

Treat this as a litigation deadline. Mark the last petition date and get an attorney involved now.

If you received Letter 3523 and the Tax Court clock is running, 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.

Call (813) 229-7100

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