ARMEN, Special Trial Judge: This case was heard pursuant to the provisions of section 7463.¹ Pursuant to section 7463(b), the decision to be entered is not reviewable by any other court, and this opinion shall not be treated as precedent for any other case.

This matter is before the Court on respondent's Motion To Dismiss For Lack Of Jurisdiction, filed February 25, 2010. Respondent moves to dismiss this case on the ground that the petition was not filed within the time prescribed by section 6213(a) or section 7502. For reasons discussed hereinafter, we shall grant respondent's motion.

At the time that the petition was filed, petitioner resided in the State of Oregon.

On October 7, 2009, respondent sent petitioner a notice of deficiency. The notice 2010 Tax Ct. Summary LEXIS 145">*146 of deficiency, which was sent to petitioner by certified mail addressed to her at her last known address, determined deficiencies in income taxes for 2006 and 2007 of $8,895 and $2,806, respectively, and accuracy-related penalties under section 6662(a) for those 2 years of $1,779 and $561.20, respectively. Petitioner received a copy of the notice of deficiency on November 16, 2009.²

The first page of the notice of deficiency included the following statement: "If you want to contest this determination in court before making any payment, you have 90 days from the date of this letter * * * to file a petition with the United States Tax Court for a redetermination of the deficiency." Also included on the first page of the notice of deficiency was the following statement: "Last Day to File a Petition With the United States Tax Court: JAN 05, 2010".^{32010 Tax Ct. Summary LEXIS 145">*147}

On Tuesday, January 19, 2010, petitioner filed a petition seeking a redetermination of the deficiencies and penalties determined by respondent in the October 7, 2009 notice of deficiency. The petition, which is dated "12/26/09", arrived at the Court by regular mail in an envelope bearing no postmark date. Affixed to the envelope was a "stamp" printed by petitioner on her personal computer using software furnished by stamps.com.⁴ This "stamp" reflects the "stamps.com" logo, "$1.39" of "US Postage First-Class", and a 5-digit number that corresponds to petitioner's ZIP Code. The "stamp" also includes two strings of alphanumeric characters whose meaning is not disclosed 2010 Tax Ct. Summary LEXIS 145">*148 in the record. As previously mentioned, the "stamp" bears no postmark and was not postmarked (or canceled) by the U.S. Postal Service, nor does a Postal Service postmark appear anywhere on the envelope itself.

As indicated, respondent filed a Motion To Dismiss For Lack Of Jurisdiction on February 25, 2010. Petitioner filed a Notice Of Objection on March 24, 2010.⁵ Respondent followed with a Response on May 25, 2010. Thereafter, a hearing on respondent's motion was held in Fresno, California, on June 14, 2010, with both parties appearing and presenting argument in support of their respective positions.^{62010 Tax Ct. Summary LEXIS 145">*149}

This Court's jurisdiction to redetermine a deficiency in income tax depends on the issuance of a valid notice of deficiency and a timely-filed petition. Rule 13(a), (c); Monge v. Commissioner,93 T.C. 22">93 T.C. 22, 93 T.C. 22">27 (1989); Normac, Inc. v. Commissioner,90 T.C. 142">90 T.C. 142, 90 T.C. 142">147 (1988). Section 6212(a) expressly authorizes the Commissioner, after determining a deficiency, to send a notice of deficiency to the taxpayer by certified or registered mail. It is sufficient for jurisdictional purposes if the Commissioner mails the notice of deficiency to the taxpayer at the taxpayer's last known address. Sec. 6212(b); Frieling v. Commissioner,81 T.C. 42">81 T.C. 42, 81 T.C. 42">52 (1983). The taxpayer, in turn, has 90 days, or 150 days if the notice is addressed to a person outside the United States, to file a petition with this Court for a redetermination of the contested deficiency. Sec. 6213(a). By virtue of section 7502, a petition that is timely mailed is deemed to be timely filed. Although timely mailing is generally determined by the postmark date, see sec. 7502(a); sec. 301.7502-1(c)(1), 2010 Tax Ct. Summary LEXIS 145">*150 Proced. & Admin. Regs., extrinsic evidence is admissible if a postmark date is either illegible or missing, see Mason v. Commissioner,68 T.C. 354">68 T.C. 354 (1977); Sylvan v. Commissioner,65 T.C. 548">65 T.C. 548 (1975).

It is clear in the present case that respondent mailed the notice of deficiency to petitioner on October 7, 2009. See Magazine v. Commissioner,89 T.C. 321">89 T.C. 321, 89 T.C. 321">327 n.8 (1987) (holding that Postal Service Form 3877 represents direct evidence of the date of mailing of the notice of deficiency); see also Clough v. Commissioner,119 T.C. 183">119 T.C. 183, 119 T.C. 183">187-188 (2002) (overruling various challenges by a taxpayer to the introduction into evidence by the Commissioner of Postal Service Form 3877). The 90th day after the date of mailing was Tuesday, January 5, 2010. However, the petition was not received and filed by the Court until Tuesday, January 19, 2010. Thus, the petition was not timely filed, and respondent's motion must be granted unless the petition is deemed to have been timely filed by virtue of having been timely mailed.

As previously mentioned, the envelope in which the petition was mailed to the Court did not bear any postmark, and both parties have proceeded on the basis that extrinsic evidence 2010 Tax Ct. Summary LEXIS 145">*151 regarding the date of mailing is therefore admissible. Under the circumstances of this case, we are content to follow the parties' approach, although we do not purport to establish a general rule applicable in all cases involving mailpieces bearing "stamps.com" postage.

Petitioner's position is succinctly set forth in her Notice Of Objection:

My original petition was filled out by me on December 25, 2009. It was mailed December 26, 2009.