OPINION OF THE COURT

The principle issue in this sentencing guideline appeal is whether a United States Sentencing Guideline § 2L2.2(b)(l) enhancement for being a previously deported illegal alien applies to an alien who left the United States under voluntary departure. Also at issue is the denial of credit for accepting responsibility under U.S.S.G. § 3El.l(a). We wifi affirm. 1

I.

Guillermo Munoz-Valencia is a Columbian citizen who was arrested on December 14, 2000 while attempting to board an airplane traveling from St. Thomas, Virgin Islands to New York. Munoz-Valencia’s arrest occurred after authorities discovered he was carrying $90,000 of undeclared currency and using a false resident alien identification card. Upon his arrest, Munoz-Valencia admitted he was an illegal alien and previously used the false identification card to enter the United States through Texas in July 2000. Munoz-Valencia pled guilty to violating 18 U.S.C. § 1546(a) for fraud and misuse of documents.

A presentence report revealed Munoz-Valencia was previously ordered deported on October 25, 1998. The immigration court issued a superseding order of voluntary departure, and Munoz-Valencia complied by returning to Columbia on November 17, 1998. On this basis, the presentence report recommended a two level enhancement under U.S.S.G. § 2L2.2(b)(l) because Munoz-Valencia was “an unlawful alien who ha[d] been deported (voluntarily or involuntarily) on one or more occasions prior to the instant offense.” U.S.S.G. § 2L2.1(b)(l). Munoz-Valencia did not object to the two level enhancement at the sentencing hearing.

The District Court adopted the recommendation of the presentence report and imposed a two level enhancement for a *485 prior deportation under U.S.S.G. § 2L2.2(b)(l). The court also found that Munoz-Valencia had not accepted responsibility for the offense under U.S.S.G. § 3El.l(a). As a result, Munoz-Valencia was sentenced to twelve months of imprisonment and three years of supervised release. Munoz-Valencia filed a motion to correct his sentence under Fed.R.Crim.P. 35(c), which was denied. This appeal followed. 2

II.

Generally, we exercise plenary review over the interpretation of sentencing guidelines. United States v. McKenzie, 193 F.3d 740, 742 (3d Cir. 1999). But where an appellant does not object, we review for plain error. United States v. Cefaratti 221 F.3d 502, 512 (3d Cir. 2000). Because Munoz-Valencia did not object to application of U.S.S.G. § 2L2.2(b)(l), we review for plain error. 3

The defendant bears the burden of showing plain error. United States v. Olano, 507 U.S. 725, 734, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993). “For there to be plain error, there must be an ‘error’ that is ‘plain’ and that ‘affects substantial rights.’ A deviation from a legal rule is ‘error.’ A ‘plain’ error is one which is ‘clear’ or ‘obvious.’” United States v. Jake, 281 F.3d 123, 132 (3d Cir. 2002) (quoting United States v. Russell, 134 F.3d 171, 180 (3d Cir. 1998)). Munoz-Valencia argues the District Court erred when it ordered a two level enhancement because § 2L2.2(b)(l) does not apply to aliens who have left the United States under a grant of voluntary departure. 4 We will affirm.

United States Sentencing Guideline § 2L2.2(a) establishes a base offense level of eight for persons found guilty of violating 18 U.S.C. § 1546, which proscribes, among other things, the fraudulent misuse of documents authorizing entry into or stay within the United States. Under U.S.S.G. § 2L2.2(b)(l), a two level enhancement applies “[i]f the defendant is an unlawful alien who has been deported (voluntarily or involuntarily) on one or more occasions prior to the instant offense.” The sentencing guidelines do not define the phrase “deported (voluntarily or involuntarily).” But we can decipher its definition by giving its words their plain, natural, and commonly understood meaning. See Hartford Underwriters Ins. Co. v. Un *486 ion Planters Bank, N.A., 530 U.S. 1, 8,120 S.Ct. 1942, 147 L.Edüd 1 (2000); United States v. Romo-Romo, 246 F.3d 1272,1275 (9th Cir. 2001).

An alien may depart the United States at his own expense if the Attorney General so permits after an immigration judge has entered an order granting voluntary departure in lieu of removal and has found that the alien:

[H]as been physically present in the United States for a period of at least one year immediately preceding the date the notice to appear was served ... is, and has been, a person of good moral character for at least 5 years immediately preceding the alien’s application for voluntary departure ... is not deportable under section 1227(a)(2)(A)(iii) or section 1227(a)(4) of this title ... [and] has established by clear and convincing evidence that the alien has the means to depart the United States and intends to do so.

8 U.S.C. § 1229c(b)(l).

An alien who departs this country under a formal deportation order is excludable from the country for five years, 8 U.S.C. § 1182, and commits a felony if he or she returns without permission. 8 U.S.C. § 1326; see Cunanan v. I.N.S., 856 F.2d 1373, 1374 n. 1 (9th Cir. 1988); 1 Bill Ong Hing, Handling Immigration Cases 394 (2d ed. 1995). A grant of voluntary departure, on the other hand, is a form of discretionary relief which allows a deportable alien to leave the United States without suffering these consequences. Cunanan, 856 F.2d at 1374 n. 1. In other words, an alien who voluntarily departs the United States may apply for immediate re-entry. 5 But a grant of voluntary departure does not exclude a deportable alien from all consequences of illegal entry or stay within this country. See Mrvica v. Esperdy, 376 U.S. 560, 84 S.Ct. 833, 11 L.Ed.2d 911 (1964). Thus, in some situations, a deport-able alien’s voluntary departure may be treated as a deportation. Id.

In Mrvica, a petitioner was under a deportation order when he departed the United States aboard a ship that sailed to Chile in 1942. Id. The ship returned to the United States shortly thereafter, where petitioner remained. Id. New deportation proceedings commenced and petitioner was again found subject to deportation but was granted the privilege of voluntary departure in a final order in 1954. Id. at 561. In 1959, following other proceedings, petitioner was ordered deported to Yugoslavia. Id. at 562. His application for status of a permanent resident under § 249 of the Immigration and *487 Nationality Act was denied on the ground that he departed the United States in 1942. Id.

Petitioner conceded he was ordered deported in 1942 and that his departure from the United States to Chile executed the order of deportation. Id. at 568. The Supreme Court said:

There can be no doubt that this ... point is correct. Legislation then applicable provided that “... any alien ordered deported ... who has left the United States shall be considered to have been deported in pursuance of law, irrespective of the source from which the expenses of his transportation were defrayed or of the place to which he departed.”

Id. (citing Act of March 4, 1929, § 1(b), 45 Stat. 1551, 8 U.S.C. (1940 ed.) § 180(b)). 6 The Court continued:

Any possible doubt of the import of this provision is removed by [legislative history] which explained ... the Department of Labor has, in many cases, after a warrant of deportation has been issued, refrained from executing the warrant and deporting the alien, at the expense of the appropriation, to the country to which he might be deported, upon the condition that the alien voluntarily, at his own expense, leave the United States. Some doubt exists whether an alien so departing has been “deported.” Subsection (b) of section 3 of the bill [the provision quoted above] therefore removes any possible doubt on this question by providing that in such cases the alien shall be considered to have been deported in pursuance of law.

Id. at 564.

The alien in Mrvica was under a deportation order when he left the United States. 376 U.S. at 561. But the Court made clear that a voluntary departure from the United States may be treated as a deportation. Id. at 563-64; see also United States v. Taofig Olabiyi Blaize, 959 F.2d 850, 851 (9th Cir. 1992) (“This case presents a single straightforward issue: If a person who is under a deportation order for which he has appealed voluntarily leaves the United States, has he been deported? We answer this question ‘yes’ based on statutes, regulations, and case authority.”). Here, as in Mrvica, an order of deportation had previously been entered against the petitioner, and there is no error, let alone plain error, in applying the U.S.S.G. § 2L2.2(b)(l) two level enhancement to an unlawful alien who has been granted voluntary departure.

III.

Munoz-Valencia contends he “accepted responsibility,” under U.S.S.G. § 3El.l(a), which permits a reduction “if the defendant clearly demonstrates acceptance of responsibility for his offense.” Whether a defendant has “accepted responsibility” requires a factual determination that we review for clear error. United States v. DeLeon-Rodriguez, 70 F.3d 764, 767 (3d Cir. 1995). “The sentencing judge is in a unique position to evaluate a defendant’s acceptance of responsibility. For this reason, the determination of the sentencing judge is entitled to great deference on review.” U.S.S.G. § 3E1.1 app. 5 (2002).

A defendant must prove by a preponderance of the evidence that a reduction is warranted under this provision. DeLeon-Rodriguez, 70 F.3d at 767. At the time of his arrest, Munoz-Valencia admitted possessing the false resident alien card for six months and using it to enter the United States illegally. 7 He points to no other *488 evidence in support of his claim that he sufficiently accepted responsibility to warrant a departure.

The District Court found MunozValeneia’s admission of possessing and using the false resident alien card insufficient to constitute acceptance of responsibility. Because Munoz-Valencia was found carrying $90,000 in undeclared currency, the District Court concluded he was “involved in something else, because [he] did not make any attempt to declare that currency.” Thus, the District Court did not “believe that [he] ha[d] accepted appropriate responsibility, and that [his] explanation was truthful.” We see no clear error.

IV.

For these reasons, we will affirm the judgment of conviction and sentence.