Time for filing petition and restrictions on assessment—(1) Time for filing petition. Within 90 days after notice of the deficiency is mailed (or within 150 days after mailing in the case of such notice addressed to a person outside the States of the Union and the District of Columbia), as provided in section 6212, a petition may be filed with the Tax Court of the United States for a redetermination of the deficiency. In determining such 90-day or 150-day period, Saturday, Sunday, or a legal holiday in the District of Columbia is not counted as the 90th or 150th day. In determining the time for filing a petition with the Tax Court in the case of a notice of deficiency mailed to a resident of Alaska prior to 12:01 p.m., e.s.t., January 3, 1959, and in the case of a notice of deficiency mailed to a resident of Hawaii prior to 4 p.m., e.d.s.t., August 21, 1959, the term “States of the Union” does not include Alaska or Hawaii, respectively, and the 150-day period applies. In determining the time within which a petition to the Tax Court may be filed in the case of a notice of deficiency mailed to a resident of Alaska after 12:01 p.m., e.s.t., January 3, 1959, and in the case of a notice of deficiency mailed to a resident of Hawaii after 4 p.m., e.d.s.t., August 21, 1959, the term “States of the Union” includes Alaska and Hawaii, respectively, and the 90-day period applies.

Restrictions on assessment. Except as otherwise provided by this section, by sections 6851, 6852, and 6861(a) (relating to termination and jeopardy assessments), by section 6871(a) (relating to immediate assessment of claims for income, estate, and gift taxes in bankruptcy and receivership cases), or by section 7485 (in case taxpayer petitions for a review of a Tax Court decision without filing bond), no assessment of a deficiency in respect of a tax imposed by subtitle A or B or chapter 41, 42, 43, or 44 of the Code and no levy or proceeding in court for its collection shall be made until notice of deficiency has been mailed to the taxpayer, nor until the expiration of the 90-day or 150-day period within which a petition may be filed with the Tax Court, nor, if a petition has been filed with the Tax Court, until the decision of the Tax Court has become final. As to the date on which a decision of the Tax court becomes final, see section 7481. Notwithstanding the provisions of section 7421(a), the making of an assessment or the beginning of a proceeding or levy which is forbidden by this paragraph may be enjoined by a proceeding in the proper court. In any case where the running of the time prescribed for filing a petition in the Tax Court with respect to a tax imposed by chapter 42 or 43 is suspended under section 6213(e), no assessment of a deficiency in respect of such tax shall be made until expiration of the entire period for filing the petition.

Exceptions to restrictions on assessment of deficiencies—(1) Mathematical errors. If a taxpayer is notified of an additional amount of tax due on account of a mathematical error appearing upon the return, such notice is not deemed a notice of deficiency, and the taxpayer has no right to file a petition with the Tax Court upon the basis of such notice, nor is the assessment of such additional amount prohibited by section 6213(a).

Tentative carryback adjustments. (i) If the district director or the director of the regional service center determines that any amount applied, credited, or refunded under section 6411(b) with respect to an application for a tentative carryback adjustment is in excess of the overassessment properly attributable to the carryback upon which such application was based, the district director or the director of the regional service center may assess the amount of the excess as a deficiency as if such deficiency were due to a mathematical error appearing on the return. That is, the district director or the director of the regional service center may assess an amount equal to the excess, and such amount may be collected, without regard to the restrictions on assessment and collection imposed by section 6213(a). Thus, the district director or the director of the regional service center may assess such amount without regard to whether the taxpayer has been mailed a prior notice of deficiency. Either before or after assessing such an amount, the district director or the director of the regional service center will notify the taxpayer that such assessment has been or will be made. Such notice will not constitute a notice of deficiency, and the taxpayer may not file a petition with the Tax Court of the United States based on such notice. However, the taxpayer, within the applicable period of limitation, may file a regular claim for credit or refund based on the carryback, if he has not already filed such a claim, and may maintain a suit based on such claim if it is disallowed or if it is not acted upon by the Internal Revenue Service within 6 months from the date the claim was filed.

The method provided in subdivision (i) of this subparagraph to recover any amount applied, credited, or refunded in respect of an application for a tentative carryback adjustment which should not have been so applied, credited, or refunded is not an exclusive method. Two other methods are available to recover such amount: (a) By way of a deficiency notice under section 6212; or (b) by a suit to recover an erroneous refund under section 7405. Any one or more of the three available methods may be used to recover any amount which was improperly applied, credited, or refunded in respect of an application for a tentative carryback adjustment.

Assessment of amount paid. Any payment made after the mailing of a notice of deficiency which is made by the taxpayer as a payment with respect to the proposed deficiency may be assessed without regard to the restrictions on assessment and collection imposed by section 6213(a) even though the taxpayer has not filed a waiver of restrictions on assessment as provided in section 6213(d). A payment of all or part of the deficiency asserted in the notice together with the assessment of the amount so paid will not affect the jurisdiction of the Tax Court. If any payment is made before the mailing of a notice of deficiency, the district director or the director of the regional service center is not prohibited by section 6213(a) from assessing such amount, and such amount may be assessed if such action is deemed to be proper. If such amount is assessed, the assessment is taken into account in determining whether or not there is a deficiency for which a notice of deficiency must be issued. Thus, if such a payment satisfies the taxpayer's tax liability, no notice of deficiency will be mailed and the Tax Court will have no jurisdiction over the matter. In any case in which there is a controversy as to the correct amount of the tax liability, the assessment of any amount pursuant to the provisions of section 6213(b)(3) shall in no way be considered to be the acceptance of an offer by the taxpayer to settle such controversy.

Jeopardy. If the district director believes that the assessment or collection of a deficiency will be jeopardized by delay, such deficiency shall be assessed immediately, as provided in section 6861(a).

Failure to file petition. If no petition is filed with the Tax Court within the period prescribed in section 6213(a), the district director or the director of the regional service center shall assess the amount determined as the deficiency and of which the taxpayer was notified by registered or certified mail and the taxpayer shall pay the same upon notice and demand therefor. In such case the district director will not be precluded from determining a further deficiency and notifying the taxpayer thereof by registered or certified mail. If a petition is filed with the Tax Court the taxpayer should notify the district director who issued the notice of deficiency that the petition has been filed in order to prevent an assessment of the amount determined to be the deficiency.

Waiver of restrictions. The taxpayer may at any time by a signed notice in writing filed with the district director waive the restrictions on the assessment and collection of the whole or any part of the deficiency. The notice must in all cases be filed with the district director or other authorized official under whose jurisdiction the audit or other consideration of the return in question is being conducted. The filing of such notice with the Tax Court does not constitute filing with the district director within the meaning of the Code. After such waiver has been acted upon by the district director and the assessment has been made in accordance with its terms, the waiver cannot be withdrawn.

Suspension of filing period for certain chapter 42 and chapter 43 taxes. The period prescribed by section 6213(a) for filing a petition in the Tax Court with respect to the taxes imposed by section 4941,4942, 4943, 4944, 4945, 4951, 4952, 4955, 4958, 4971, or 4975, shall be suspended for any other period which the Commissioner has allowed for making correction under § 53.4963-1(e)(3). Where the time for filing a petition with the Tax Court has been suspended under the authority of this paragraph (e), the extension shall not be reduced as a result of the correction being made prior to expiration of the period allowed for making correction.