Regulations promulgated under this section address compliance with the statutory requirement. Sec. 1.6851-2, Income Tax Regs. The regulation discusses the conditions under which a certificate will be issued to a departing alien:

(b) Issuance of certificate of compliance. -- (1) In general. (i) Upon the departure of an alien required to secure a certificate of compliance under paragraph (a) of this section, the district director shall determine whether the departure of such alien jeopardizes the collection of any income tax for 98 T.C. 695">*699 the current or the preceding taxable year, but the district director may determine that jeopardy does not exist in some cases. If the district director finds that the departure of such an alien results in jeopardy, the taxable period of the alien will be terminated, and the alien will be required to file returns and make1992 U.S. Tax Ct. LEXIS 52">*59 payment of tax in accordance with subparagraph (3)(iii) of this paragraph. On the other hand, if the district director finds that the departure of the alien does not result in jeopardy, the alien will be required to file the statement on returns required by subparagraph (2) or (3)(ii) of this paragraph, but will not be required to pay income tax before the usual time for payment.

(ii) The departure of an alien who is a resident of the United States or a possession thereof (or treated as a resident under section 6013(g) or (h)) and who intends to continue such residence (or treatment as a resident) shall be treated as not resulting in jeopardy, and thus not requiring termination of his taxable period, except when the district director has information indicating that the alien intends by such departure to avoid the payment of his income tax. In the case of a nonresident alien (including a resident alien discontinuing residence), the fact that the alien intends to depart from the United States will justify termination of his taxable period unless the alien establishes to the satisfaction of the district director that he intends to return to the United States and that his departure1992 U.S. Tax Ct. LEXIS 52">*60 will not jeopardize collection of the tax. The determination of whether the departure of the alien results in jeopardy will be made on examination of all the facts in the case. Evidence tending to establish that jeopardy does not result from the departure of the alien may be provided, for example, by information showing that the alien is engaged in trade or business in the United States or that he leaves sufficient property in the United States to secure payment of his income tax for the taxable year and of any income tax for the preceding year which remains unpaid.

[Sec. 1.6851-2(b)(1), Income Tax Regs.]

Issuance of a certificate does not necessarily constitute an acceptance of the departing alien's returns as filed. The determination as to the issuance of a certificate is based on the question of whether the departure of the taxpayer jeopardizes the collection of income tax for the current or the preceding taxable year. Given that the certificate was issued, we assume that respondent's agents determined that petitioner's departure did not jeopardize the collection of tax. Sec. 1.6851-2(b)(1)(i), Income Tax Regs. Where respondent finds that collection of the tax will not be1992 U.S. Tax Ct. LEXIS 52">*61 jeopardized, the statute provides that payment of any tax shall not be enforced by any proceedings prior to the expiration of the time otherwise allowed for paying such taxes. Sec. 6851(d)(2). Thus, the language of section 6851(d) does not restrict the period of time respondent has to determine a deficiency in tax, nor does it 98 T.C. 695">*700 require her to alter her methods or procedures with respect to determining a deficiency in the tax of a departing alien to whom a certificate has been issued. We conclude that respondent's issuance of the certificate, in and of itself, does not preclude her from later determining a deficiency.

Petitioner challenges the deficiency on grounds that the determination thereof violates the Due Process Clause of the Constitution of the United States. U.S. Const. amend. V. Petitioner argues that "Due process requires that the IRS not contradict itself and thereby breach the trust of a taxpayer." As a general matter, the fact that the notice of deficiency sets forth a position "different" from that taken by respondent's agent in issuing the certificate does not violate a taxpayer's right to due process of the laws. As we discussed above, the certificate1992 U.S. Tax Ct. LEXIS 52">*62 does not represent a finding on the part of respondent that petitioner's 1988 Form 1040-NR was correct as filed. Accordingly, we reject petitioner's argument that due process prohibits respondent from issuing a notice of deficiency under the facts of this case. ⁴

Petitioner argues that respondent should be estopped from determining a deficiency for 1988. Equitable estoppel is a judicial doctrine that "precludes a party from denying his own acts or representations which induced another to act to his detriment." Graff v. Commissioner,74 T.C. 743">74 T.C. 743, 74 T.C. 743">761 (1980), affd. 673 F.2d 784">673 F.2d 784 (5th Cir. 1982); see also Kennedy v. United States,965 F.2d 413">965 F.2d 413 (7th Cir. 1992). Estoppel is applied against the Commissioner "with utmost caution and 1992 U.S. Tax Ct. LEXIS 52">*63 restraint." Estate of Emerson v. Commissioner,67 T.C. 612">67 T.C. 612, 67 T.C. 612">617 (1977). Traditional elements of equitable estoppel include: (1) Conduct constituting a representation of material fact; (2) actual or imputed knowledge of such fact by the representor; (3) ignorance of the fact by the representee; (4) actual or imputed expectation by the representor that the representee will act in reliance upon the representation; (5) actual reliance thereon; and (6) detriment on the part of the representee. 74 T.C. 743">Graff v. Commissioner, supra at 761. Detrimental reliance on the part of the party seeking to invoke estoppel is a key condition. Boulez v. Commissioner,76 T.C. 209">76 T.C. 209, 76 T.C. 209">215 (1981), affd. 810 F.2d 98 T.C. 695">*701 209 (D.C. Cir. 1987); Hudock v. Commissioner,65 T.C. 351">65 T.C. 351, 65 T.C. 351">363 (1975). The burden of proof is on the party claiming estoppel against the Government. Rule 142(a); Estate of Emerson v. Commissioner,67 T.C. 612">67 T.C. 612, 67 T.C. 612">618 (1977).

Petitioner failed in his burden of proof. The facts in this case do not establish many of1992 U.S. Tax Ct. LEXIS 52">*64 the elements necessary for estoppel, including the requisite reliance by petitioner. As the certificate was issued subsequent to the filing of petitioner's 1988 return, he cannot be said to have relied on it in completing the return. Further, petitioner has not presented evidence of detriment caused by any reliance on respondent's actions. 76 T.C. 209">Boulez v. Commissioner, supra at 215. Accordingly, respondent is not estopped from issuing a notice of deficiency under the facts of this case.

Having reached this conclusion, we address the substantive adjustment determined in the notice of deficiency. Section 55, imposing the AMT, is expressly made applicable to nonresident alien individuals engaged in a trade or business within the United States. Sec. 871(b)(1). Petitioner does not maintain that he is not liable for the AMT. Rather, his argument focuses on the manner in which the amount of the tax is determined and, specifically, the exemption amount used in making that computation. He argues that the statutory scheme, which provides for exemption amounts based upon filing status, discriminates against married nonresident aliens and nonresident aliens 1992 U.S. Tax Ct. LEXIS 52">*65 who are Swiss nationals. Because his spouse did not have U.S. source income for 1988, and thus was not required to file a U.S. income tax return, petitioner argues that he was deprived of the benefit of the increased exemption amount applied in the case of a joint return filed by married taxpayers. He further argues that this scheme treats him less favorably than single taxpayers, the exemption amount for whom is greater than the amount available in the case of a married taxpayer filing a separate return.

As we have recognized, "the power of Congress in levying taxes is very wide, and where a classification is made of taxpayers that is reasonable, and not merely arbitrary and capricious, the Fifth amendment can not apply." Barr v. Commissioner,51 T.C. 693">51 T.C. 693, 51 T.C. 693">695 (1969) (quoting Barclay & Co. v. Edwards,267 U.S. 442">267 U.S. 442, 267 U.S. 442">450 (1924)). The treatment of which petitioner complains originates in section 6013, which provides 98 T.C. 695">*702 that taxpayers who are husband and wife may file joint Federal income tax returns. Sec. 6013(a). However, a taxpayer whose spouse is a nonresident alien may not file a joint income tax return. 1992 U.S. Tax Ct. LEXIS 52">*66 Sec. 6013(a)(1). Since petitioner's spouse was a nonresident alien for the tax year in question, petitioner could not file a joint return, but rather was required to file a separate return. This restriction applies equally to all taxpayers whose spouses are nonresident aliens, regardless of their nationality. Schinasi v. Commissioner,53 T.C. 382">53 T.C. 382, 53 T.C. 382">384 (1969). Consequently, petitioner is not discriminated against based upon his national origin. Black v. Commissioner,69 T.C. 505">69 T.C. 505 (1977); Bhargava v. Commissioner,T.C. Memo. 1978-197, affd. 603 F.2d 211">603 F.2d 211 (2d Cir. 1979). We note that the sometimes differential treatment afforded taxpayers filing joint returns, vis-a-vis taxpayers filing separate or single returns, has been challenged as unconstitutional on various theories. We have consistently denied such challenges. See DeMars v. Commissioner,79 T.C. 247">79 T.C. 247 (1982) (requirement that married couples aggregate income does not unconstitutionally discriminate against married persons); Black v. Commissioner,69 T.C. 505">69 T.C. 505, 69 T.C. 505">510 (1977)1992 U.S. Tax Ct. LEXIS 52">*67 (requirement that child care credit be claimed on joint return not unconstitutional); Brady v. Commissioner,T.C. Memo. 1983-163 (classification based on marital status not unconstitutional). Similarly, challenges have been made against other provisions affecting nonresident aliens, also without success. See 53 T.C. 382">Schinasi v. Commissioner, supra (restriction on filing joint return with nonresident alien spouse not unconstitutional); 51 T.C. 693">Barr v. Commissioner, supra (restriction on dependency deduction for nonresident aliens not unconstitutional).

In his final argument, petitioner argues that the statute operates in this case to violate provisions of the tax treaty in effect between the United States and Switzerland. Petitioner alleged in his petition to this Court as follows:

the Swiss-US Tax Treaty implies that Swiss persons taxable in the US not be discriminated against if compared to other persons in similar circumstances. The fact that a tax exemption of only US $ 20,000.00 was granted to petitioner by the IRS, whereby he could have asserted US $ 40,000.00 as a US-Resident, violates the treaty. 1992 U.S. Tax Ct. LEXIS 52">*68 This violation is all the more significant, since even non resident-aliens filing as single persons would be treated more favourably, since they could claim an exemption of US $ 30,000.

98 T.C. 695">*703 The treaty provision on which petitioner bases his argument provides as follows:

(3) The citizens of one of the contracting States shall not, while resident in the other contracting State, be subjected therein to other or more burdensome taxes than are the citizens of such other contracting State residing in its territory. The term "citizens" as used in this Article includes all legal persons, partnerships and associations created or organized under the laws in force in the respective contracting States. In this Article the word "taxes" means taxes of every kind or description, whether Federal, State, cantonal, municipal or communal. [Convention on Double Taxation of Income, May 24, 1951, United States-Switzerland, Art. XVIII, par. (3), 2 U.S.T. (Part 2) 1751, 1761, 1955-2 C.B. 814, 820.]

The tax provisions applied to petitioner in this case do not discriminate against petitioner based upon his status as a citizen of Switzerland. Petitioner's conclusion1992 U.S. Tax Ct. LEXIS 52">*69 that, if he were a U.S. resident, he would be able to claim the $ 40,000 exemption amount allowed in the case of a joint return, is incorrect. Even if petitioner were a U.S.citizen, he nevertheless would be required to file as married filing separate since his spouse is a nonresident alien. Sec. 6013(a)(1). As discussed above, this restriction applies to all taxpayers whose spouses are nonresident aliens, regardless of the taxpayers' nationality or citizenship status. Accordingly, this statute does not treat petitioner differently from citizens of the United States under similar circumstances. The fact that section 55(d) provides for different exemption amounts depending on filing status also does not discriminate against Swiss nationals in violation of the tax treaty where the statute is equally applicable to taxpayers who are U.S. citizens and those who are not. Accordingly, we hold that the statutes limiting the exemption amount applicable in computing petitioner's AMT do not violate the United States-Switzerland tax treaty.

Generally, section 55 imposes a tentative minimum tax on the alternative minimum taxable income of a taxpayer which exceeds the applicable exemption1992 U.S. Tax Ct. LEXIS 52">*70 amount. Sec. 55(b)(1). The applicable exemption amount is found in section 55(d), the amount of which is determined based on the taxpayer's filing status. A $ 40,000-exemption amount is available in the case of a joint return or a surviving spouse; a $ 30,000-exemption amount is available in the case of an unmarried individual; and a $ 20,000-exemption amount is available in the case of a 98 T.C. 695">*704 married individual filing a separate return. Sec. 55(d)(1)(A)(C). Petitioner, a married individual, filed a separate return and, hence, is entitled only to the $ 20,000 exemption amount for purposes of computing the tentative minimum tax. Consequently, we sustain respondent's determination.

Respondent also determined that petitioner is liable for the addition to tax for negligence pursuant to section 6653(a)(1). Negligence is defined as lack of due care or failure to do what a reasonable and prudent person would do under the circumstances. Neely v. Commissioner,85 T.C. 934">85 T.C. 934, 85 T.C. 934">947 (1985). Petitioner has the burden of proof to establish that he is not liable for that addition to tax. Rule 142(a); Bixby v. Commissioner,58 T.C. 757">58 T.C. 757, 58 T.C. 757">791-792 (1972).1992 U.S. Tax Ct. LEXIS 52">*71 Petitioner argues that he attempted in good faith to complete his 1988 return.

Based on this record, we conclude that the underpayment was not due to negligence or intentional disregard of rules and regulations. Petitioner otherwise completed his tax return accurately and substantiation of any expenses claimed as deductions on the return is not at issue.

For the foregoing reasons,

Decision will be entered for respondent with respect to the deficiency and for petitioner regarding the addition to tax.