Judge KEARSE concurs in a separate opinion.
MESKILL, Circuit Judge:Petitioner-appellant Donald Green (Green) appeals an order of the United States District Court for the Western District of New York, Curtin, J., denying his motion for an extension of time to file a motion for relief pursuant to 28 U.S.C. § 2255 as amended by the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA). Section 2255 provides, in pertinent part:
A prisoner in custody under sentence of a court established by Act of Congress claiming the right to be released upon the ground that the sentence was imposed in violation of the Constitution or laws of the United States, or that the court was without jurisdiction to impose such sentence, or that the sentence was in excess of the maximum authorized by law, or is otherwise subject to collateral attack, may move the court which imposed the sentence to vacate, set aside or correct the sentence-
Congress imposed a “1-year period of limitation” on section 2255 motions, which runs, in 'this case, from “the date on which the judgment of conviction becomes final.”1 28 U.S.C. § 2255(1).
The district court held that Green’s time to file a section 2255 motion had already expired because his conviction became final more than one year before he filed his motion requesting an extension of time. We granted Green a certificate of appeala-bility on the following issues: (1) whether a district court can grant an extension of *81time to file a section 2255 motion, (2) whether a timely motion for extension of time can be construed as a section 2255 motion for purposes of timeliness under the AEDPA, and (3) what date constitutes the date on which the judgment of conviction becomes final under the AEDPA.
We vacate the district court’s order because we find that the district court did not have jurisdiction to rule on Green’s motion for an extension of time absent the filing of a substantive section 2255 motion. In view of the facts of this case, however, the government has offered to waive its statute of limitations defense to permit Green to file a section 2255 motion.
BACKGROUND
A. Green’s Trial and Appeal
On March 30, 1994, a jury returned guilty verdicts against Green for, inter alia, racketeering conspiracy, narcotics conspiracy, engaging in a continuing criminal enterprise and obstruction of justice, all arising out of Green’s role as the leader of the “L.A. Boys” gang in Buffalo, New York. See United States v. Workman, 80 F.3d 688, 691-92 (2d Cir.1996) (holding, on direct appeal, that the evidence showed “that Green was the leader of the L.A. Boys, and that he had orchestrated the enterprise’s activities”). The district court sentenced Green to four concurrent life sentences, two concurrent twenty year sentences, a ten year concurrent sentence and fifteen concurrent four year sentences, all to follow an unexpired New York state murder sentence. Final judgment entered on July 29, 1994.
On March 27, 1996, we affirmed Green’s conviction in all respects.2 See id. The United States Supreme Court denied Green’s petition for writ of certiorari on October 21, 1996. See Green v. United States, 519 U.S. 955, 117 S.Ct. 373, 136 L.Ed.2d 262 (1996).
B. Green’s Motion to Extend Time
On June 10, 1997, Green filed with the district court a “motion for [sic] extend time” to enlarge the time within which he could file a motion for relief pursuant to section 2255. The government opposed the motion on the ground that Green’s time to move pursuant to section 2255 had expired on March 29, 1997, one year after we affirmed Green’s convictions on direct appeal. On November 18, 1997, Green moved the district court to treat his previous motion for an extension of time as a motion for relief under section 2255. The government opposed this motion on timeliness grounds, and alternatively, argued that Green had not set forth sufficiently a claim for relief under section 2255.
On December 15, 1997, the district court summarily denied Green’s motion for an extension of time on the grounds that Green’s time to move pursuant to section 2255 had expired on July 29, 1995, one year after his conviction in the district court became final. Because Green had filed his first motion for an extension of time on June 10, 1997, the district court held that Green’s time to file had lapsed and accordingly, that it was without jurisdiction to consider Green’s motion.
On December 26, 1997, Green filed a timely notice of appeal. Green, incarcerated and pro se, tried for over two years to obtain appellate review of the district court’s denial of his motion. On March 1, 2000, we granted Green a certificate of *82appealability and ordered assignment of appellate counsel. This appeal followed.
DISCUSSION
The questions authorized by the certificate of appealability are questions of law, which we review de novo. See Triana v. United States, 205 F.3d 36, 40 (2d Cir.), cert. denied, 531 U.S. 956, 121 S.Ct. 378, 148 L.Ed.2d 292 (2000).
A. Whether a District Court Can Grant an Extension of Time to File a Section 2255 Motion
In answering the first question, we look to two of our prior decisions. In United States v. Leon, 203 F.3d 162 (2d Cir.2000) (per curiam), we held that “a federal court lacks jurisdiction to consider the timeliness of a § 2255 petition until a petition is actually filed.” Id. at 164. Prior to an actual filing, “there is no case or controversy to be heard, and any opinion we were to render on the timeliness issue would be merely advisory.” Id.; see also, e.g., United States Nat’l Bank of Or. v. Indep. Ins. Agents of Am., 508 U.S. 439, 446, 113 S.Ct. 2173, 124 L.Ed.2d 402 (1993) (reaffirming the principle that “a federal court [lacks] the power to render advisory opinions” (quotation marks omitted)).3
Green has not yet filed a section 2255 motion with the district court. We concluded, in Leon, that “[i]f or when [petitioner] actually files a § 2255 petition, the District Court and this court may consider his argument that such a petition should be considered timely.” 203 F.3d at 164. Ordinarily, therefore, a federal court would not have jurisdiction to consider Green’s motion to extend time.
Less than two weeks after we granted the certificate of appealability, we decided Smith v. McGinnis, 208 F.3d 13 (2d Cir.), cert. denied, 531 U.S. 840, 121 S.Ct. 104, 148 L.Ed.2d 63 (2000). In Smith, we “join[ed] our sister circuits” in holding that the AEDPA’s “one-year period [under 28 U.S.C. § 2244] is a statute of limitations rather than a jurisdictional bar so that courts may equitably toll the period.” Id. at 17 (citing Calderon v. United States Dist. Court for the Cent. Dist. of Cal., 163 F.3d 530, 541 (9th Cir.1998) (en banc)). We hold that the one year deadline the AEDPA imposed on the filing of section 2255 petitions similarly established a statute of limitations and is not a jurisdictional bar. See Moore v. United States, 173 F.3d 1131, 1134 (8th Cir.1999) (noting that “[s]ection 2255 refers to the time limit as a ‘period of limitation’ and as a ‘limitation period’ ”). We cautioned in Smith, however, that “[e]quitable tolling applies only in ... rare and exceptional circumstance[s],” Smith, 208 F.3d at 17 (internal quotation marks omitted), and only where the defendant has “acted with reasonable diligence throughout the period he seeks to toll.” See id. (citing Johnson v. Nyack Hosp., 86 F.3d 8, 12 (2d Cir.1996)); see also Valverde v. Stinson, 224 F.3d 129, 133-36 (2d Cir.2000) (conducting equitable tolling analysis with respect to an untimely section 2254 petition); Warren v. Garvin, 219 F.3d 111, 113-14 (2d Cir.2000) (same).
Two principles emerge from our decisions in Leon and Smith: a district court may grant an extension of time to file a motion pursuant to section 2255 only if (1) the moving party requests the extension upon or after filing an actual section 2255 motion, and (2) “rare and exception*83al” circumstances warrant equitably tolling the limitations period.
B. Whether a Timely Motion for Extension of Time Can Be Construed as a Section 2255 Motion for Purposes of Timeliness under the AEDPA
It is well settled that pro se litigants generally are entitled to a liberal construction of their pleadings, which should be read “to raise the strongest arguments that they suggest.” Graham v. Henderson, 89 F.3d 75, 79 (2d Cir.1996) (quotation marks omitted); see Haines v. Kerner, 404 U.S. 519, 520, 92 S.Ct. 594, 30 L.Ed.2d 652 (1972) (per curiam) (holding that the allegations in a pro se complaint are “h[e]ld to less stringent standards than formal pleadings drafted by lawyers”); Liriano v. United States, 95 F.3d 119, 122 (2d Cir.1996) (per curiam) (pro se supplemental brief “substantially constitutes the motion envisioned by § 2244(b)(3)(A), and will be treated' as satisfying the motion requirement”).
We see no reason why the general rule should not apply to pro se motions filed pursuant to section 2255. Where a motion, nominally seeking an extension of time, contains allegations sufficient to support a claim under section 2255, a district court is empowered, and in some instances may be required, under Haines to treat that motion as a substantive motion for relief under section 2255. See Fleming v. United States, 146 F.3d 88, 90 (2d Cir.1998) (per curiam) (holding that a district court must review pro se petitions “with a lenient eye, allowing borderline cases to proceed”) (quoting Williams v. Kullman, 722 F.2d 1048, 1050 (2d Cir.1983)); cf. United States v. Ben-Shimon, 249 F.3d 98, 103-04 (2d Cir.2001) (per curiam) (general objection of pro se defendant at sentencing should have been construed liberally for preservation purposes). In so holding, we note that the reference in the second certified question to a “timely motion for extension of time” is irrelevant to our holding. Irrespective of when a prisoner files a motion for extension of time, the district court must first determine whether the motion contains allegations supporting a claim for relief under section 2255. If it does, the district court should construe it as such, and then decide whether the motion is timely. If it does not, the district court has no jurisdiction under Leon to consider the motion.4
Although we reject the government’s sweeping contention that a motion to extend time can never be converted into -a substantive motion under section 2255, the government’s argument is persuasive with respect to Green’s filings. A motion under section 2255 must “specify all the grounds for relief which are available to the movant and of which he has or, by the exercise of reasonable diligence, should have knowledge and shall set forth in summary form the facts supporting each of the grounds thus specified.” Rules Governing Section 2255 Proceedings, Rule 2(b); see United States v. Horvath, 157 F.3d 131, 132-33 (2d Cir.1998) (per curiam) (facts supporting claimed error need only be set forth generally).
Courts are often called on to determine whether a moving party’s generalized *84allegations are sufficient to meet the requirements of section 2255. See, e. g., United States v. Aiello, 814 F.2d 109, 113 (2d Cir.1987) (holding that a section 2255 petition must be based on more than “[a]iry generalities, conclusory assertions and hearsay statements”). Here, however, Green’s June 10, 1997 and September 15, 1997 requests for an extension of time do not contain a single reference to any cognizable claim under section 2255. Nor does Green’s November 18, 1997 motion to treat his prior motion as a section 2255 motion. Accordingly, because Green had not articulated any basis in fact or in law for relief under section 2255, the district court did not err by failing to treat his motion to extend time as a substantive section 2255 motion. See, e. g., Barnett v. United States, 870 F.Supp. 1197, 1201 (S.D.N.Y.1994) (“Although district courts employ substantial leniency in interpreting motion papers that pro se petitioners submit, it is simply impossible for this Court to determine whether petitioner has made out a case for relief on these six claims because petitioner has failed to state both the grounds on which relief is requested and any facts that would substantiate these grounds.”).
C. When Does a Conviction Become Final Under Section 2255?
The government argued before the district court that Green’s conviction had become final for purposes of the AEDPA on March 29, 1996, when we upheld his conviction on direct appeal. The district court held that Green’s conviction became final when it was entered by the trial court on July 29, 1994. Neither the government’s prior position nor the district court’s holding on this point was correct.
Since the district court issued its order denying Green’s motion as untimely, we have held that a prisoner’s conviction becomes final under section 2255 of the AEDPA when the United States Supreme Court denies the prisoner’s petition for a writ of certiorari. See Leon, 203 F.3d at 163. Therefore, Green’s conviction became final on October 21, 1996 when the United States Supreme Court denied his petition for a writ of certiorari. He had until October 21, 1997 to move for relief under section 2255. Green filed his motion to extend time, dated June 10, 1997, and renewed it on September 15, 1997, well before the deadline. Accordingly, the district court’s determination that any section 2255 motion filed by Green after July 29, 1995 would have been time-barred was erroneous.
D. The Government’s Waiver of its Statute of Limitations Defense
On appeal, the government concedes that it and the district court erred in determining when Green’s conviction became final and that this Court should remand to allow Green the opportunity to move under section 2255. The government suggests, however, that we allow Green only thirty days within which to file and that we restrict his arguments to “those previously raised, by appellant in his pleadings filed below.”5 Green counters that the statutory time period should be equitably tolled from the date of his initial motion to extend time, June 10, 1997, leaving him 133 days to move. See, e. g., Smith, 208 F.3d *85at 17 (holding that AEDPA’s time limitation may be equitably tolled where “extraordinary circumstances” prevent petitioner from filing a timely petition and where petitioner acts with reasonable diligence).
We do not reach Green’s arguments regarding equitable tolling because (1) Green has not filed a motion for relief under section 2255 as required under Leon, and (2) such a discussion is not contemplated by the certificate of appealability. See 28 U.S.C. § 2253(c)(3) (“The certificate of ap-pealability ... shall indicate which specific issue or issues satisfy the showing required” . for appellate review under the AEDPA.); see also Armienti v. United States, 234 F.3d 820, 824 (2d Cir.2000) (“We will not address a claim not included in the certificate of appealability.”). Accordingly, we have no jurisdictional basis to address Green’s equitable tolling arguments.
Nevertheless, in its brief, the government expressly waives its statute of limitations defense by advocating a remand and “suggesting” the conditions for that remand. See, e. g., United States v. Gould, 1997 WL 535821, at *4 (E.D.Pa. July 29, 1997) (“[T]he limitations period in AEDPA is a statute of limitations subject to tolling and waiver. Because the government has waived the statute of limitations defense, the court will proceed to evaluating the merits of the defendant’s motion.”). During oral argument, the government confirmed that it had waived its statute of limitations defense and was “leaving it to [the Court] to fashion what’s fair.”
In light of the government’s concession, the clear error made by both the government and the district court and the fact that Green is incarcerated, we believe that Green should be given sixty days from the date this decision becomes final to move the district court for relief under section 2255. Further, we find no rational basis for the government’s desire to limit the grounds upon which Green may rely in support of such a motion.
CONCLUSION
We vacate the judgment of the district court but do not remand because our jurisdiction ends with our decision on the issues presented in the certificate of appealability. We assume, however, that, by the government’s offer, it has committed itself to waive its statute of limitations defense to Green’s filing a section 2255 motion within 60 days fróm the date this decision becomes final without limitation as to the claims Green may assert therein.
. The statutory "period of limitations” provision reads:
A 1-year period of limitation shall apply to a motion under this section. The limitation period shall run from the latest of—
(1) the date on which the judgment of conviction becomes final;
(2) the date on which the impediment to making a motion created by governmental action in violation of the Constitution or laws of the United States is removed, if the movant was prevented from making a motion by such governmental action;
(3) the date on which the right asserted was initially recognized by the Supreme Court, if that right has been newly recognized by the Supreme Court and made retroactively applicable to cases on collateral review; or
(4) the date on which the facts supporting the claim or claims presented could have been discovered through the exercise of due diligence.
28 U.S.C. § 2255.
. Both Green and the government cite March 29, 1996 as the date on which we affirmed Green’s conviction. That decision is dated March 27, 1996. See Workman, 80 F.3d at 688. The two day discrepancy does not alter our analysis.
. Our jurisdiction vested when the Court granted Green a certificate of appealability. See Soto v. United States, 185 F.3d 48, 52 (2d Cir.1999) ("[A] certificate of appealability [even if] issued erroneously nevertheless suffices to confer appellate jurisdiction under § 2253.”).
. If the district court decides to construe a motion for extension of time as a substantive section 2255 motion, the court should notify the movant of the consequences of the court's action and offer the movant the opportunity to withdraw the motion rather than have the court consider it as a request for relief under section 2255. The notice to the movant should describe the limitations placed by the applicable rules on amending a section 2255 motion, and the potentially adverse effects if the motion is denied with prejudice and the movant then faces the stringent limits on second or successive section 2255 motions.
. Specifically, the government argues that Green should be limited to the allegations asserted in his November 18, 1997 motion to treat his motion to extend time as a motion under section 2255 before the district court, and his March 16, 1998 and November 10, 1998 motions before this Court. In these post-deadline filings, unlike in his pre-dead-line requests for an extension, Green advanced substantive arguments for relief under section 2255.