Letter 3219-B: The Notice of Deficiency for a Corporation, Estate, or Trust

What the notice actually says

The IRS describes Letter 3219-B as a notice of its "intent to assess a tax deficiency and of your right to petition the U.S. Tax Court," issued because "we received information from third parties that doesn't match the information you reported on your return." It comes from the BMF Underreporter program, which matches payer information against business-master-file income tax returns; the IRS's own explainer speaks to Form 1120 corporations and Form 1041 estates and trusts.

The package, per IRM 4.119.4.21.11, holds the letter itself, Form 4089, Notice of Deficiency - Waiver, a copy of the latest Letter 2030 or recomputed Letter 2030 (without its first page and response page), the payer-information prints behind the proposed change, and Publication 1. The amounts can differ from the Letter 2030; the IRS explains that "you cannot challenge all items in tax court," so the notice may show a different figure than the earlier letter.

Letter 3219-B is the business-account counterpart to CP3219A, the individual notice after a CP2000. (See the IRS Notice Library for the rest of the family.)

What actually triggered it

The BMF Underreporter case usually starts with Letter 2531, an inquiry, or Letter 2030, a proposed adjustment. The IRS manual says a Letter 3219-B "may be sent as a follow up to the Letter 2030" (IRM 4.119.4.1.3). "May" is accurate: the case can also close with no change, or move to an examination, so a Letter 2030 does not always lead here.

IRC §6212(a) authorizes the notice, and IRC §6213(a) bars the IRS from assessing the deficiency until it mails the notice and the petition period runs. Under IRM 4.119.4.21.11, the IRS mails a Letter 3219-B by certified mail to an address inside the United States and by registered mail to an address outside it.

Response deadline and what happens if you miss it

IRC §6213(a) gives "90 days, or 150 days if the notice is addressed to a person outside the United States," counted from the mailing date, and moves a last day that falls on a Saturday, a Sunday, or a legal holiday in the District of Columbia to the next day that is none of those. The BUR manual repeats it: the period "is statutory and IRS employees cannot extend it."

Treat the last date printed on the letter as the deadline. The final sentence of §6213(a) makes a petition filed on or before "the last date specified for filing such petition by the Secretary in the notice of deficiency" timely. For example, a Letter 3219-B mailed on Tuesday, July 14, 2026 reaches day 90 on Monday, October 12, 2026, Indigenous Peoples' Day, a legal holiday in the District of Columbia, so the last day to petition is Tuesday, October 13, 2026.

If the period ends with no petition and no agreement, the IRS assumes its changes are correct and assesses the deficiency, and the entity receives a bill for the tax, interest, and any penalties. From there the options are to pay in full and sue for a refund, or, with information the IRS never considered, to ask for audit reconsideration; the Appeal Channel Router covers when that route fits.

The practitioner's actual next step

Calendar the last day first: count from the mailing date, compare it with the printed date, and keep the earlier. Then compare the notice with the last Letter 2030 line by line, because the figures can differ.

If the entity agrees, sign and return Form 4089; the IRS says doing so limits additional interest, and without a payment it will send a bill.

If the entity disagrees, do two things at once. Mail the IRS the documents that resolve the mismatch, at the address on the notice, with the notice attached; the IRS says that response "won't extend your deadline." And file a petition with the U.S. Tax Court before the last day; the Court's petitioner page has the form and filing guidance.

Ask about rescission if the notice rests on a clear error or the entity wants IRS Appeals. The manual allows the IRS, with the entity's written consent on Form 8626 and managerial approval, to rescind a Letter 3219-B issued in error, when the entity shows it owes less, or when it asks for Appeals with enough time left on the assessment statute. The IRS will not rescind once 90 or fewer days remain on that statute (unless the entity extends it), once the petition period has run, or once a petition is filed (IRM 4.119.4.21.11.1.1). Until the rescission takes effect, the 90 days keep running.

A notice of deficiency stops the IRS's clock to assess the new tax, not the collection clock on tax already assessed; the CSED Calculator explains the difference.

What Letter 3219-B gets confused with — and why the distinction matters

The costly confusion is with Letter 2030. Letter 2030 proposes the change and asks for a response by the date it states; Letter 3219-B determines the deficiency and starts a fixed Tax Court clock. An entity that answers Letter 3219-B the way it answered Letter 2030, by writing back and waiting, can lose the right to go to the Tax Court.

The second is with CP3219A. Both follow an underreporter mismatch and both carry the same 90-day rule, but CP3219A goes to an individual and encloses Form 5564; Letter 3219-B goes to a corporation, estate, or trust and encloses Form 4089.

The third is with the examination notices, Letter 3219 and Letter 531. Those follow an audit and come with an examination report; Letter 3219-B follows a document-matching review and comes with the Letter 2030 figures and the payer prints.

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