                     FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

ISMAEL TABLADA,                            
               Petitioner-Appellant,
                                                 No. 07-35538
                 v.
J.E. THOMAS,* Warden, Federal                     D.C. No.
                                                CV 06-00762-MO
Correction Institute, Sheridan,
                                                     OPINION
Oregon,
              Respondent-Appellee.
                                           
        Appeal from the United States District Court
                 for the District of Oregon
        Michael W. Mosman, District Judge, Presiding

                    Argued and Submitted
               March 7, 2008—Portland, Oregon

                         Filed July 3, 2008

Before: Marsha S. Berzon and Carlos T. Bea, Circuit Judges,
         and Philip S. Gutierrez,** District Judge.

                   Opinion by Judge Gutierrez




   *J.E. Thomas is substituted for his predecessor Charles Daniels
as Warden of the Federal Correction Institute, Sheridan, Oregon. Fed. R.
App. P. 43(c)(2).
   **The Honorable Philip S. Gutierrez, United States District Judge for
the Central District of California, sitting by designation.

                                 8071
                    TABLADA v. THOMAS                  8073


                        COUNSEL

Stephen R. Sady, Chief Deputy Federal Public Defender,
Portland, Oregon, for petitioner-appellant Ismael Tablada.

Karin J. Immergut, United States Attorney, Scott E. Asphaug,
Assistant United States Attorney, and Kelly A. Zusman,
Assistant United States Attorney, Portland, Oregon, for the
respondent-appellee.


                        OPINION

GUTIERREZ, District Judge:

  In this appeal, we consider whether the Bureau of Prisons
(“BOP”) violated the Administrative Procedure Act (“APA”)
8074                     TABLADA v. THOMAS
in promulgating 28 C.F.R. § 523.20, the regulation interpret-
ing 18 U.S.C. § 3624(b), which governs the calculation of
good conduct time for federal prisoners. The district court
held that the BOP’s interpretation in § 523.20 was reasonable
and that it did not violate § 706(2)(A) of the APA. Accord-
ingly, the district court denied the petitioner’s habeas petition
which challenged the BOP’s calculation of the length of time
the petitioner had left to serve on his sentence. The BOP has
conceded it violated § 706(2)(A) of the APA by failing to
articulate a rational basis for its decision to promulgate
§ 523.20. We hold that the remedy for this violation is to
interpret the federal statute in accordance with the BOP’s Pro-
gram Statement 5880.28, and so affirm.

I.       BACKGROUND & PROCEDURE

   Ismael Tablada is an inmate at the Federal Correctional
Institute in Sheridan, Oregon. Tablada was convicted of a nar-
cotics offense in the District of Minnesota. On December 17,
1990, he was sentenced to a 20-year term of imprisonment,
followed by 10 years of supervised release. As of February
2007, Tablada’s projected release date, taking into consider-
ation his good time credit, was April 16, 2008.1

   On October 31, 2006, Tablada filed an amended petition
for writ of habeas corpus pursuant to 28 U.S.C. § 2241. In the
petition, Tablada challenges the BOP’s calculation of good
time credits pursuant to the good time credit statute, 18 U.S.C.
§ 3624(b). Tablada contends that in promulgating its method
for calculation of good time conduct credit in 28 C.F.R.
§ 523.20 and Program Statement 5880.28, Sentence Computa-
     1
   Tablada’s projected release date has passed. This fact, however, does
not render his appeal moot because his sentence includes a term of super-
vised release. See Mujahid v. Daniels, 413 F.3d 991, 994-995 (2005)
(“The ‘possibility’ that the sentencing court would use its discretion to
reduce a term of supervised release under 18 U.S.C. § 3583(e)(2) was
enough to prevent the petition from being moot”).
                          TABLADA v. THOMAS                          8075
tion Manual (CCCA of 1984), the BOP failed to articulate a
rational basis for its interpretation of the federal statute, thus
violating 5 U.S.C. § 706(2)(A).2

  A.    Good Time Credit Statute, 18 U.S.C. § 3624(b)

  Title 18 U.S.C. § 3624 governs the timing of federal pris-
oners’ release from custody. Section 3624(b) provides in rele-
vant part:

      (b) Credit toward service of sentence for satisfactory
      behavior.—

      (1) . . . a prisoner who is serving a term of impris-
      onment of more than 1 year other than a term of
      imprisonment for the duration of the prisoner’s life,
      may receive credit toward the service of the prison-
      er’s sentence, beyond the time served, of up to 54
      days at the end of each year of the prisoner’s term
      of imprisonment, beginning at the end of the first
      year of the term, subject to determination by the
      Bureau of Prisons that, during that year, the prisoner
      has displayed exemplary compliance with institu-
      tional disciplinary regulations. . . . [C]redit for the
      last year or portion of a year of the term of imprison-
      ment shall be prorated and credited within the last
      six weeks of the sentence.

18 U.S.C. § 3624(b)(1) (emphasis added).
  2
   Tablada’s habeas corpus petition also claimed the BOP regulation and
Program Statement are invalid because they violate the APA, 5 U.S.C.
§ 553, which requires a notice and comment period, and the Ex Post Facto
Clause. The district court rejected both claims. Tablada has abandoned
these claims by failing to raise them in his brief on appeal. See Blanchard
v. Morton Sch. Dist., 509 F.3d 934, 938 (9th Cir. 2007).
8076                  TABLADA v. THOMAS
  B.   BOP Program Statement and Regulation

   Since the passage of 18 U.S.C. § 3624(b) in 1984, the BOP
has interpreted good time credit to be based on the time
served by the prisoner. In November 1988, the BOP’s general
counsel issued an internal memorandum advising staff of the
procedures for awarding good time credits under § 3624(b).
The memorandum recited the text of § 3624(b), and stated
that “good conduct time is earned on sentences of 1 year and
1 day or more at a rate of 54 days for each year of time
served.” (emphasis added). In February 1992, BOP formal-
ized this interpretation of § 3624 via the BOP Program State-
ment 5880.28.

   In September 1997, the BOP published for comment as an
interim rule 28 C.F.R. § 523.20, which was the BOP’s inter-
pretation of § 3624(b). 62 Fed. Reg. 50786-01 (Sept. 26,
1997). The commentary to the interim rule stated that “[t]he
awarding and vesting of good conduct time at a rate of 54
days per year (prorated when the time served by the inmate
for the sentence during the year is less than a full year) ha[s]
been clearly stated by statute since the implementation of the
Sentencing Reform Act of 1984.” Id. at 50786. The BOP
received no public comments, and, in 2003, published a
change to the proposed rule and again accepted comments. 68
Fed. Reg. 37776-01 (June 25, 2003). On December 5, 2005,
28 C.F.R. § 523.20 became final. 70 Fed. Reg. 66752-01
(Nov. 3, 2005). 28 C.F.R. § 523.20 provides:

    (a) For inmates serving a sentence for offenses com-
    mitted on or after November 1, 1987, but before
    September 13, 1994, the Bureau will award 54 days
    credit toward service of sentence (good conduct time
    credit) for each year served. This amount is prorated
    when the time served by the inmate for the sentence
    during the year is less than a full year.
                           TABLADA v. THOMAS                            8077
28 C.F.R. § 523.20(a) (emphasis added).3

   In accordance with the BOP’s regulatory scheme, the pris-
oner does not earn the first 54 days of good time credit until
after completing 365 days of incarceration. Mujahid, 413 F.3d
at 996. During the last year of incarceration, the BOP prorates
the good time credits, awarding the prisoner 0.148 days credit
[54/365 = 0.148] for every day actually served that year.
Pacheco-Camacho v. Hood, 272 F.3d 1266, 1267-1268 (9th
Cir. 2001). The BOP’s admittedly “complicated” mathemati-
cal formula yields, for a model federal prisoner with a 10-year
sentence, a maximum of 470 days of good time credit, which
includes no credit when the prisoner is not in prison. Id. at
1269.

   The BOP’s interpretation of the good time conduct statute
led to the filing of numerous lawsuits by federal prisoners.
Like Tablada, these prisoners contested the methodology by
which the BOP computes good time credit under
§ 3624(b)(1), reading the statute as awarding good time credit
based on the sentence imposed rather than the time served.
Under their interpretation, a model federal prisoner with a 10-
year sentence would be entitled to 540 days of credit [54
days/yr x 10yrs = 540], rather than the 470 days awarded
under the BOP’s method. Faced with these competing inter-
pretations of § 3624(b), we have upheld the validity of the
BOP’s interpretation of “term of imprisonment” in § 3624(b)
as meaning time served rather than sentence imposed. See
Pacheco-Camacho, 272 F.3d at 1271.

   In Pacheco-Camacho, we noted that § 523.20 was adopted
through the APA’s notice-and-comment procedure, and that
  3
    This version of 28 C.F.R. § 523.20 is different from the version quoted
by the district court in his order. The district court used a previous version
of the regulation which was effective until December 4, 2005. However,
the distinctions between the previous version and the amended regulation,
quoted here, do not affect the analysis.
8078                      TABLADA v. THOMAS
the BOP’s interpretation of § 3624(b) via § 523.20 was there-
fore entitled to full Chevron deference.4 Id. at 1268 (citing
Chevron, 467 U.S. 837). Applying the first step of the
Chevron analysis, we looked at both the plain language of the
statute and its legislative history, and found that the meaning
of “term of imprisonment” as used in § 3624(b) was ambigu-
ous. Id. at 1269-70. Proceeding to the second Chevron step,
we then asked whether the BOP’s interpretation was “reason-
able.” Id. at 1270. Answering in the affirmative, we con-
cluded that the BOP’s interpretation “comports with the
statutory language of section 3624(b), and does not subvert
the statutory design.” Id.

   Nearly four years later we revisited the same issue in
Mujahid, 413 F.3d at 998. Citing Pacheco-Camacho, we reaf-
firmed the reasonableness of the BOP’s interpretation of
§ 3624(b). Id. at 999 (“Mujahid’s position rests on an inter-
pretation of this statute at odds with binding authority of this
court”).

  Notwithstanding our decisions in Pacheco-Camacho and
Mujahid, Tablada filed this habeas petition, but under a differ-
ent theory. Unlike the previous challenges to the reasonable-
ness of the BOP’s construction of § 3624(b), Tablada instead
contends that the BOP has not complied with the require-
ments of the APA, 5 U.S.C. § 706, because it has not articu-
  4
    Under Chevron, the Court must first determine “whether Congress has
directly spoken to the precise question at issue. If the intent of Congress
is clear,” then the Court “must give effect to the unambiguously expressed
intent of Congress.” Chevron U.S.A., Inc. v. Natural Resources Defense
Council, Inc., 467 U.S. 837, 842-843 (1984). Next, “if the statute is silent
or ambiguous with respect to the specific issue, the question for the court
is whether the agency’s answer is based on a permissible construction of
the statute.” Id. at 843. “If a statute is ambiguous, and if the implementing
agency’s construction is reasonable, Chevron requires a federal court to
accept the agency’s construction of the statute, even if the agency’s read-
ing differs from what the court believes is the best statutory interpreta-
tion.” Nat’l Cable & Telecomms. Ass’n v. Brand X Internet Servs., 545
U.S. 967, 980 (2005) (citations omitted).
                      TABLADA v. THOMAS                     8079
lated a rational basis for its decision to promulgate its
interpretation of the statute. The United States District Court
for the District of Oregon found that Pacheco-Camacho and
Mujahid prevented it from considering Tablada’s APA chal-
lenge, since the Ninth Circuit had already determined that the
BOP’s method for calculating good time credit was reason-
able. This timely appeal followed.

   After the parties submitted briefing on the instant case, we
addressed the very procedural issue raised by Tablada in
Arrington v. Daniels, 516 F.3d 1106 (9th Cir. 2008). In
Arrington, the petitioners brought petitions for habeas corpus
which challenged 28 C.F.R. § 550.58(a)(1)(vi)(B), a BOP reg-
ulation which categorically excluded prisoners with convic-
tions involving a firearm or other dangerous weapon or
explosives from eligibility for early release under 18 U.S.C.
§ 3621(e). Id. at 1109. Reversing the district court’s denial of
the petitions, the Ninth Circuit held that the rule violated the
APA, 5 U.S.C. § 706, because the administrative record con-
tained no rationale explaining the BOP’s decision for the cate-
gorical exclusion. Id. at 1114. The district court had identified
two possible rational bases for the BOP decision: “(1) the
increased risk that offenders with convictions involving fire-
arms might pose to the public and (2) the need for uniformity
in the application of the eligibility regulation.” Id. at 1113
(citations omitted). The Ninth Circuit found the first rationale,
articulated only in the BOP’s brief and not contained in the
administrative record, was “precisely the type of ‘post hoc
rationalization [ ]’ of appellate counsel that we are forbidden
to consider in conducting review under the APA.” Id. (empha-
sis and alteration in original) (citing Burlington Truck Lines,
Inc. v. United States, 371 U.S. 156, 168 (1962)). As for the
second rationale, the Ninth Circuit found it inadequate
because the BOP offered no explanation for why it chose cat-
egorical exclusion of prisoners with convictions involving
firearms to achieve uniformity, rather than categorical inclu-
sion of prisoners with nonviolent convictions involving fire-
8080                  TABLADA v. THOMAS
arms, which would achieve the stated goal of uniformity. Id.
at 1114.

   The BOP now concedes that the regulation governing good
time conduct credits suffers the same procedural infirmity as
the regulation in Arrington, because the BOP failed to articu-
late in the administrative record the rationale upon which it
relied when it promulgated the good time credit regulation.

II.    STANDARD OF REVIEW

  We review a district court’s denial of a writ of habeas cor-
pus pursuant to 28 U.S.C. § 2241 de novo. Id. at 1112.

   In reviewing the BOP’s conduct, we consider whether the
agency’s promulgation of the final rule is “arbitrary, capri-
cious, an abuse of discretion, or otherwise not in accordance
with law.” 5 U.S.C. § 706(2)(A). We conduct this review
based solely on the administrative record and determine
whether the agency has articulated a rational basis for its deci-
sion. Arrington, 516 F.3d at 1112 (citing Motor Vehicle Mfrs.
Ass’n of U.S., Inc. v. State Farm Mut. Auto. Ins., 463 U.S. 29,
50 (1983)).

III.   DISCUSSION

   [1] In light of the BOP’s concession that it failed to articu-
late in the administrative record a rationale for the interpreta-
tion of § 3624(b)(1) promulgated in § 523.20, the only
remaining issue, then, is to determine the appropriate remedy.
The BOP contends that any relief in this case should be lim-
ited to a procedural correction, allowing the BOP’s long-
standing practice governing good conduct sentencing credits
to continue until the procedural correction is effected. Tablada
asks us to grant his habeas petition and order the BOP to cal-
culate his good conduct time based on his interpretation of the
good time credit statute.
                      TABLADA v. THOMAS                     8081
  A.   Deference to the BOP Interpretation of § 3624(b)

   [2] Since its promulgation of Program Statement 5880.28
in 1992, the BOP has interpreted § 3624(b) to refer to time
served, rather than sentence imposed. Thus, even if we take
the invalid regulation out of the equation, we are left with an
interpretation of § 3624(b) that bases good time credit on time
served rather than sentence imposed.

   An agency’s rules are entitled to two possible levels of def-
erence. Generally, Chevron deference is reserved for legisla-
tive rules that an agency issues within the ambit of the
authority entrusted to it by Congress. See United States v.
Mead Corp., 533 U.S. 218, 226-227 (2001). Such rules are
characteristically promulgated only after notice and comment.
Id. at 230. If, on the other hand, the agency rule or decision
is not within an area of express delegation of authority or does
not purport to have the force of law, it is entitled to a measure
of deference proportional to its power to persuade, in accor-
dance with the principles set forth in Skidmore v. Swift & Co.,
323 U.S. 134 (1944). See Mead, 533 U.S. at 228, 234. Under
this level of review, we look to the process the agency used
to arrive at its decision. Id.; Skidmore, 323 U.S. at 140.
Among the factors we consider are the “interpretation’s thor-
oughness, rational validity, [ ] consistency with prior and sub-
sequent pronouncements,” the “ ‘logic[ ] and expertness’ of
an agency decision, the care used in reaching the decision, as
well as the formality of the process used.” The Wilderness
Society v. U.S. Fish & Wildlife Serv., 353 F.3d 1051, 1068
(9th Cir. 2003) (citing Skidmore, 323 U.S. at 140 and Mead,
533 U.S. at 228).

   Program Statement 5880.28 does not purport to carry the
force of law and was not adopted after notice and comment.
We therefore do not accord it Chevron deference. However,
because Program Statement 5880.28 is an internal agency
guideline, “akin to an ‘interpretive rule’ that ‘do[es] not
require notice and comment,’ ” Reno v. Koray, 515 U.S. 50,
8082                   TABLADA v. THOMAS
61 (1995) (quoting Shalala v. Guernsey Mem. Hosp., 514
U.S. 87, 99 (1995)), we believe it is entitled to a measure of
deference under Skidmore. We conclude that the Program
Statement 5880.28 does meet the Skidmore standard, and thus
provides the appropriate interpretation of § 3624. We turn
now to the reasons underlying this conclusion.

  B.   Application of Deference under Skidmore

   Applying the factors articulated in Skidmore, we find that
the methodology utilized in Program Statement 5880.28 is
both persuasive and reasonable. Under Skidmore, one of the
factors we consider is the “rational validity” of the agency
decision. See The Wilderness Society, 353 F.3d at 1068. In
Pacheco-Camacho and Mujahid, we already determined that
the BOP’s interpretation of § 3624(b) via its regulation,
§ 523.20, is “reasonable.” See Mujahid, 413 F.3d at 998;
Pacheco-Camacho, 272 F.3d at 1270-1271. Because Program
Statement 5880.28 provides an interpretation of the federal
statute identical to that in § 523.20, our conclusion in
Pacheco-Camacho regarding the reasonableness of § 523.20
applies to it with equal force.

   [3] In Pacheco-Camacho, we found that the BOP’s meth-
odology for calculating good time conduct credits was reason-
able because it “comports with the statutory language of
section 3624(b) . . . .” Pacheco-Camacho, 272 F.3d at 1270.
In particular, we examined the statutory language of
§ 3624(b) and focused on its final sentence, which reads,
“credit for the last year or portion of a year of the term of
imprisonment shall be prorated and credited within the last
six weeks of the sentence.” Id. at 1268-69 (emphasis in origi-
nal) (quoting 18 U.S.C. § 3624(b)(1)). Under the BOP’s read-
ing of the statute, “the model prisoner will ordinarily receive
his fifty-four-day credit after complying with prison disciplin-
ary rules for 365 days . . . .” Id. (emphasis in original). During
the last year or portion of a year of the prisoner’s sentence,
the BOP would prorate the 54 days of credit a year to 0.148
                      TABLADA v. THOMAS                     8083
day of credit for every actual day served during good behavior
(54/365 = 0.148). Id. at 1267-68. Like Tablada, the plaintiff
in Pacheco-Camacho read the statute as awarding good time
credit based on the sentence imposed, so a prisoner with a ten-
year sentence would receive 54-days per year multiplied by
ten years, or 540 days. We found the plaintiff’s reading incon-
sistent with a statute that contemplates prorating credit for the
last year of imprisonment. See id. at 1269. We pointed out
that under the plaintiff’s interpretation (or in this case Tabla-
da’s), the model prisoner would receive a 54-day credit after
serving only 311 days (365 days - 54 days), thus conferring
a “windfall” on prisoners. Id. We noted that “[n]othing in the
statute clearly suggests that Congress intended to give the
prisoner such a windfall in his last year.” Id. Likewise in
Mujahid, we reaffirmed the BOP’s interpretation of § 3624(b)
as reasonable and subject to deference. See Mujahid, 413 F.3d
at 997.

   [4] In addition to the statutory language, we also discussed
in Pacheco-Camacho the legislative history of § 3624, and
determined that the BOP’s methodology for calculating good
time conduct credits “does not subvert the statutory design.”
Pacheco-Camacho, 272 F.3d at 1270. By enacting § 3624,
Congress sought to simplify the computation of good time
credits which, under its predecessor statute, computed good
time credits after every month served. Id. at 1269. Thus,
unlike the earlier scheme which called for calculating good
time credits at different monthly rates depending on the length
of the prison term and which allowed prison officials discre-
tion to withhold and restore credits depending on the inmate’s
subsequent behavior, the new system embodied in § 3624
envisioned that a prisoner could calculate with certainty the
time of his release. Id. Acknowledging the complexity of the
BOP’s computation method, we explained that “Congress
chose to tolerate the additional complexity in order to arrive
at a more equitable result,” namely “an effective and fair pro-
rating scheme, enabling inmates to calculate with reasonable
certainty the end of their imprisonment . . . .” Id. at 1270. In
8084                   TABLADA v. THOMAS
sum, based on our reasoning in Pacheco-Camacho and
Mujahid, we find that the methodology utilized in Program
Statement 5880.28 has “rational validity.”

   [5] Another factor we consider under Skidmore is whether
the agency has applied its position consistently. Mead, 533
U.S. at 228; Good Samaritan Hosp. v. Shalala, 508 U.S. 402,
417 (1993). Here, BOP Program Statement 5880.28 has been
in effect for at least sixteen years, since its implementation in
1992. See Bowen v. Hood, 202 F.3d 1211, 1221-1222 (9th
Cir. 2000) (treating unambiguous language in a program
statement as binding upon the BOP). Moreover, Program
Statement 5880.28 incorporated the same sentencing credit
methodology the BOP had been practicing since 1987.
Tablada has not identified any instances where the BOP used
any other methodology for calculating good time credits,
including the methodology he proposes. We may thus assume
that for more than twenty years, the BOP has consistently
implemented its policy of calculating good time credits based
on time served rather than sentence imposed.

   [6] While Tablada and others may have asserted a reason-
able alternative interpretation, i.e., calculating good time cred-
its based on sentence imposed rather than time served, the
consistent and even application of the BOP’s methodology
promulgated in Program Statement 5880.28 since 1992 con-
vinces us that we must accord deference to the BOP’s inter-
pretation. To change course now would have an extremely
disruptive effect on the BOP’s administration of the release of
federal prisoners. Given this consideration, as well as the rea-
sonableness of the BOP’s interpretation of § 3624(b)(1) dis-
cussed in Pacheco-Camacho, we conclude that the BOP’s
methodology for calculating good time credits in Program
Statement 5880.28 is reasonable and persuasive.

   Finally, we address Tablada’s argument that the United
States Sentencing Commission (“Commission”) has provided
the appropriate standard by which to interpret § 3624. Tablada
                           TABLADA v. THOMAS                            8085
insists that the Commission has interpreted the good time
credit statute to mean a prisoner earns credit on each year of
the sentence imposed. He contends that the fact that the Com-
mission interprets § 3624 in this manner means that the
“proper remedy” for the BOP’s APA violation is to imple-
ment Tablada’s interpretation, rather than the time served rule
unless and until the BOP adopts a regulation complying with
the APA that passes judicial muster.

   Congress charged the Commission with establishing sen-
tencing ranges for offenses, 28 U.S.C. § 994(b), and
instructed it, “as a starting point in its development of the ini-
tial sets of guidelines,” to ascertain the average sentences
imposed and length of terms served prior to creation of the
Commission. 28 U.S.C. § 994(m).5 The Commission then
engaged in a statistical analysis of data from thousands of sen-
tences, and presented the results in the “Levels Table” in June
1987. See United States Sentencing Commission, Supplemen-
tary Report on the Initial Sentencing Guidelines and Policy
Statements, at 27-39. Table 1(a), “Estimated Time Served for
Baseline Offenses: 1st Time Offenders, Convicted at Trial,
Sentenced to Prison, Adjusted for Good Time” presents a sta-
tistical analysis of average sentences. See id.

  In the Supplementary Report, the Commission provided a
definition of the term “adjusted for good time”:
  5
    28 U.S.C. § 994(m) states: “The Commission shall insure that the
guidelines reflect the fact that, in many cases, current sentences do not
accurately reflect the seriousness of the offense. This will require that, as
a starting point in its development of the initial sets of guidelines for par-
ticular categories of cases, the Commission ascertain the average sen-
tences imposed in such categories of cases prior to the creation of the
Commission, and in cases involving sentences to terms of imprisonment,
the length of such terms actually served. The Commission shall not be
bound by such average sentences, and shall independently develop a sen-
tencing range that is consistent with the purposes of sentencing described
in section 3553(a)(2) of title 18, United States Code.”
8086                      TABLADA v. THOMAS
      Adjusted for good time.” Prison time was increased
      by dividing by 0.85 good time when the term
      exceeded 12 months. This adjustment corrected for
      the good time (resulting in early release) that would
      be earned under the guidelines. This adjustment
      made sentences in the Levels Table comparable with
      those in the guidelines (which refer to sentences
      prior to the awarding of good time).

Id. at 23.

   Tablada asserts that every federal prisoner has a term of
imprisonment imposed based on a Sentencing Table that
assumes good time credit based on 15% of the sentence
imposed.6 He claims that because the Commission was acting
in its authority to interpret the Sentencing Reform Act—
including § 3624(b) covering good time credit—the Commis-
sion’s (and Tablada’s interpretation) should prevail.

   We are not persuaded by Tablada’s argument. First, if the
Commission felt the BOP was erroneously interpreting
§ 3624(b), it had ample opportunity to make its objections
known during the notice and comment periods for 28 C.F.R.
§ 523.20, in September 1997 and June 2003. The Commis-
sion, however, remained silent. Second and more importantly,
we have already found that the BOP is the agency charged
with interpreting the good time credit statute. See Pacheco-
Camacho, 272 F.3d at 1270 (“While the statute does not
explicitly vest the BOP with the authority to determine the
basis for the proration of good time credits, this power is
implied by the BOP’s statutory authority [under 18 U.S.C.
§ 3624] to award good time credits to inmates serving federal
sentences”). For these reasons, Tablada’s argument cannot
stand.
  6
   Tablada’s interpretation of the statute results in a prisoner being eligi-
ble for a 15% reduction in his sentence, whereas the BOP’s interpretation
results in an approximately 13% reduction.
                       TABLADA v. THOMAS                      8087
IV.   CONCLUSION

   The BOP has admitted it violated § 706(2)(A) of the APA
in failing to set forth a valid rationale for its interpretation of
the federal good time credit statute when it promulgated 28
C.F.R. § 523.20. Nevertheless, invalidating § 523.20 leaves in
place the same interpretation of § 3624(b) contained in BOP
Program Statement 5880.28. We conclude that the BOP’s
methodology for calculating good time credits in Program
Statement 5880.28 is both reasonable and persuasive under
Skidmore. We therefore affirm the district court’s denial of
Tablada’s petition for habeas corpus.

  AFFIRMED
