Rule 35 Sentence Reductions in Federal Court

By Elizabeth Franklin-Best, Esq., and Christopher Zoukis, JD, MBA

Federal Rule of Criminal Procedure 35 is a narrow but important tool. It allows a federal sentence to be changed after it is imposed — in two specific situations. One corrects a clear error in the sentence very soon after sentencing. The other reduces a sentence to reward substantial assistance the defendant provided to the government. Both are limited, both are governed by strict timing, and both are worth understanding.

At Elizabeth Franklin-Best, P.C., Rule 35 deadlines are built into how we plan every federal sentencing and cooperation matter. Elizabeth Franklin-Best, our principal attorney — recognized by Best Lawyers in America as a 2026 “Best Lawyer” in Appellate Practice and ranked by Chambers USA 2026 for Litigation: White-Collar Crime & Government Investigations — is the author of Reversing Your Criminal Conviction. Across more than 330 federal proceedings, her practice has centered on sentencing and post-judgment relief — sentence-reduction motions, First Step Act § 404 resentencings, and the landmark resentencing decision in Aiken v. Byars, 410 S.C. 534, 765 S.E.2d 572 (2014), in which she served as counsel — the same sentence-adjustment terrain Rule 35 occupies. Managing Director Christopher Zoukis keeps the firm focused on every lawful avenue for adjusting a sentence. Rule 35 sentence reductions are governed by Federal Rule of Criminal Procedure 35.

This guide explains Rule 35 — the two parts of the rule, the correction of a clear error under Rule 35(a), the substantial-assistance reduction under Rule 35(b), the strict timing each carries, and how Rule 35 differs from other post-conviction tools. If a Rule 35 issue is in play in your case, this guide explains what the rule does and does not allow.

Quick Answer

Question	Answer
What is Rule 35?	A Federal Rule of Criminal Procedure that allows a court to change a sentence after it is imposed, in two narrow situations.
What is Rule 35(a)?	The provision that allows correction of a sentence resulting from arithmetical, technical, or other clear error — within 14 days of sentencing.
What is Rule 35(b)?	The provision that allows the court, on a government motion, to reduce a sentence for the defendant’s substantial assistance provided after sentencing.
What is the deadline for a Rule 35(b) motion?	Generally within one year of sentencing, with later filing permitted in defined circumstances where the assistance became useful later.
Can I file a Rule 35(b) motion myself?	No. A Rule 35(b) reduction requires a motion from the government.
Can Rule 35(b) go below a mandatory minimum?	Yes. Rule 35(b)(4) expressly allows the court to reduce the sentence below the minimum established by statute.
What is the first step with our firm?	A paid, one-hour initial consultation assessing whether the 14-day clear-error window, a cooperation posture, or another sentence-adjustment tool applies.

Key Takeaways

• Rule 35 allows a federal court to change a sentence after it is imposed, in two narrow situations.
• Rule 35(a) corrects a sentence resulting from a clear error, but only within 14 days of sentencing.
• Rule 35(a) is for an obvious mistake — not for the court to reconsider its sentencing judgment.
• Rule 35(b) allows a reduction, on a government motion, for substantial assistance provided after sentencing.
• Rule 35(b) fills the gap when valuable cooperation, such as later testimony, occurs after the sentence is imposed.
• A Rule 35(b) motion is generally filed within one year, with later filing allowed in defined circumstances.
• A Rule 35(b) reduction requires a government motion — the defendant cannot file it alone.
• Rule 35 is distinct from a 2255 motion, a 3582(c)(2) reduction, and compassionate release.
• A Rule 35(b) reduction can go below a statutory mandatory minimum — Rule 35(b)(4) says so expressly.
• Under Wade v. United States, courts review a refusal to file a substantial-assistance motion only for unconstitutional motive or a decision not rationally related to a legitimate government end.

What Is Rule 35?

Rule 35 of the Federal Rules of Criminal Procedure is the rule that allows a federal court to change a sentence after it has been imposed — in two narrowly defined situations. It is, by design, a limited rule. Once a sentence is pronounced, a court’s authority to alter it is constrained, and Rule 35 is one of the few mechanisms that authorizes a change.

The rule has two distinct parts, and they do very different things. Rule 35(a) allows the court to correct a sentence that resulted from a clear error, but only within a very short window after sentencing. Rule 35(b) allows the court, on a government motion, to reduce a sentence to reflect a defendant’s substantial assistance to the government.

Because the two parts of Rule 35 serve different purposes and run on different timing, it is important to keep them separate. The sections below address each in turn.

Rule 35(a): Correcting a Clear Error

Rule 35(a) is the error-correction provision. It allows the sentencing court to correct a sentence that resulted from arithmetical, technical, or other clear error.

The defining feature of Rule 35(a) is its extremely short window. The rule’s text provides: “Within 14 days after sentencing, the court may correct a sentence that resulted from arithmetical, technical, or other clear error.” Two details matter. First, Rule 35(c) defines “sentencing” as the oral announcement of the sentence — the clock starts in the courtroom, not when the written judgment is entered. Second, filing a notice of appeal does not take this power away: Federal Rule of Appellate Procedure 4(b)(5) expressly preserves the district court’s authority to correct a sentence under Rule 35(a) even after an appeal is noticed. Once the 14 days pass, however, the court loses its Rule 35(a) authority, and a clear error must be addressed, if at all, through other means such as a direct appeal.

Rule 35(a) is also narrow in substance. It is meant for a clear error — an obvious mistake, such as an arithmetical miscalculation or a plain technical error in the sentence. It is not a vehicle for the court to reconsider its sentencing judgment, to reweigh the factors, or to change its mind about an appropriate sentence. When a genuine clear error exists, however, Rule 35(a) is the fastest way to fix it — and the short deadline means it must be raised immediately.

Applied Insight: The Rule 35(a) window is so short that it is easy to lose. If a clear error in the sentence is spotted — a miscalculation, a plain technical mistake — it must be raised within days, not weeks. Attentive review of the sentence immediately after the hearing is the only way to use Rule 35(a) effectively; once the window closes, the same error becomes a much harder problem.

Rule 35(b): Substantial Assistance

Rule 35(b) is the substantial-assistance provision, and in practice it is the part of Rule 35 most often used. It allows the court, on a government motion, to reduce a sentence to reflect a defendant’s substantial assistance in the investigation or prosecution of another person.

Rule 35(b) addresses a specific timing problem in cooperation cases. A defendant’s cooperation does not always conclude before sentencing — sometimes the most valuable assistance, such as testimony at a co-defendant’s trial, happens afterward. A pre-sentencing substantial-assistance motion under Guideline § 5K1.1 cannot capture that later help. Rule 35(b) fills the gap: it allows the government to move, after sentencing, to reduce the sentence based on assistance the defendant provided after the sentence was imposed.

A Rule 35(b) reduction can be significant, and it is the mechanism that makes it possible for a cooperating defendant who is sentenced before testifying to still receive the benefit of that cooperation. Like a pre-sentencing substantial-assistance motion, the size of any reduction is decided by the court.

The Timing of a Rule 35(b) Motion

Rule 35(b) has its own timing rules, separate from the short Rule 35(a) window.

The general rule, set by Rule 35(b)(1), is that the government may move for a reduction within one year of sentencing — and because Rule 35(c) defines sentencing as the oral announcement, the year runs from the day the sentence is pronounced. But the rule recognizes that some cooperation only becomes useful later. Under Rule 35(b)(2), the government may move more than one year after sentencing if the substantial assistance involved any of three situations:

1. information not known to the defendant until one year or more after sentencing;
2. information the defendant provided within the year that did not become useful to the government until more than a year after sentencing; or
3. information whose usefulness the defendant could not reasonably have anticipated until more than a year after sentencing, and which the defendant promptly provided once its usefulness became apparent.

One more timing rule helps cooperators whose help straddles the sentencing date. Under Rule 35(b)(3), when the court evaluates whether the post-sentencing assistance was substantial, it may also consider the defendant’s presentence assistance — though help already rewarded through a § 5K1.1 departure cannot be counted twice.

This flexibility matters in practice. A cooperating defendant whose testimony or assistance is needed years down the road still has a path to a reduction through Rule 35(b), provided the circumstances fit the rule. The timing analysis is fact-specific, and it is one of the things counsel evaluates in a cooperation case.

Rule 35(b) Can Go Below a Mandatory Minimum

For defendants sentenced under a statutory mandatory minimum, Rule 35(b) carries unusual power. Rule 35(b)(4) states that when acting under Rule 35(b), the court “may reduce the sentence to a level below the minimum sentence established by statute.”

That makes Rule 35(b) one of the very few mechanisms in federal law that can take a sentence beneath a mandatory floor — the post-sentencing counterpart to a motion under 18 U.S.C. § 3553(e) at the original sentencing. In drug and firearm cases where a mandatory minimum drove the sentence, post-sentencing cooperation followed by a government Rule 35(b) motion may be the only realistic route to a term below that floor. We factor this into the advice we give cooperating clients from the first conversation.

The Government Controls a 35(b) Motion

There is one feature of Rule 35(b) that a defendant must understand clearly: the motion belongs to the government.

A Rule 35(b) reduction requires a motion from the government. The defendant cannot file a Rule 35(b) motion on their own behalf, and the court generally cannot grant a Rule 35(b) reduction without the government’s motion. Whether to file the motion — and whether the assistance was substantial enough to warrant it — is, in the first instance, the government’s judgment.

The Supreme Court defined the narrow checks on that discretion in Wade v. United States, 504 U.S. 181 (1992). Wade holds that the substantial-assistance condition gives the government “a power, not a duty” to file the motion, and that courts may review a refusal only if it was based on an unconstitutional motive — race or religion, for example — or was not rationally related to any legitimate government end. A defendant who merely shows that the assistance was substantial is not entitled to relief, or even to discovery or an evidentiary hearing, without a substantial threshold showing of improper motive. Wade arose under § 3553(e) and § 5K1.1, and courts apply the same framework to Rule 35(b).

This is the same dynamic that governs a pre-sentencing substantial-assistance motion, and it carries the same lesson. A cooperating defendant is, to a significant degree, relying on the government’s good-faith assessment of the value of the cooperation. A plea agreement that expressly promises a Rule 35(b) motion can give the defendant additional, agreement-based arguments — a separate question Wade did not decide — but absent such a promise, the reduction depends on the government’s decision to seek it. Understanding that reality is part of evaluating any cooperation arrangement.

Rule 35(b) vs. § 5K1.1: Two Cooperation Tracks

Federal law rewards substantial assistance through two parallel tracks, divided by the moment the sentence is announced. Guideline § 5K1.1 operates at sentencing: on the government’s motion, the court may depart downward to reflect assistance the defendant provided before that day. Rule 35(b) operates after sentencing: on the government’s motion, the court may reduce the already-imposed sentence to reflect assistance provided once the case was over.

The tracks share their architecture — both require a government motion, both leave the size of the reduction to the court, and both are subject to the limited Wade review described above — but the temporal boundary is firm. Cooperation completed before sentencing belongs in a § 5K1.1 motion; cooperation that continues afterward belongs in Rule 35(b), with Rule 35(b)(3) letting the court weigh the presentence help when judging whether the later assistance was substantial.

One current note: the Sentencing Commission’s November 2025 amendments eliminated most Guideline departures, but § 5K1.1 survived — it remains in the 2025 Guidelines Manual, and the substantial-assistance system continues to function on both sides of the sentencing date.

Rule 35 vs. Other Post-Conviction Relief

Rule 35 is one of several tools that can change a federal sentence, and it is worth distinguishing it from the others.

Rule 35(a) corrects a clear error in the sentence and operates only in the days right after sentencing. Rule 35(b) rewards post-sentencing cooperation and requires a government motion. Neither is a challenge to the legality of a conviction — that is the role of a 2255 motion. Neither is based on a retroactive Guideline amendment — that is the role of a 3582(c)(2) sentence reduction. And neither is based on extraordinary and compelling personal circumstances — that is the role of compassionate release.

Because each tool has its own trigger, a defendant may be eligible for one and not another. A thorough post-conviction review considers all of them and identifies which, if any, fits the case. Rule 35 is the right tool when there is a clear sentencing error caught immediately, or when post-sentencing substantial assistance has been provided.

How Our Firm Approaches Rule 35

Rule 35 rewards lawyers who move fast and plan ahead, and we do both. Elizabeth Franklin-Best — admitted to practice before the U.S. Supreme Court and every federal circuit court of appeals — treats the 14-day clear-error review as a standard step after each sentencing hearing, and we map the Rule 35(b) timeline into every cooperation strategy from the outset.

Our Rule 35 work includes reviewing the sentence promptly after the hearing so that any clear error can be raised within the short Rule 35(a) window, advising cooperating clients on how Rule 35(b) can capture post-sentencing assistance, advocating with the government on the value of a client’s cooperation, and analyzing the Rule 35(b)(2) exceptions where assistance comes well after sentencing. Admitted to the U.S. Supreme Court and every federal circuit and appearing pro hac vice from Montana to Florida, we take Rule 35 matters in district courts in every part of the country.

For related reading, see our federal post-conviction relief overview and our guides to cooperation and substantial assistance and sentence reductions.

Talk With a Federal Lawyer

Rule 35 is narrow, but in the right situation it is valuable — a fast fix for a clear sentencing error, or a path to a reduction for post-sentencing cooperation. Both parts of the rule are governed by strict timing, so they must be on counsel’s radar.

A paid, one-hour initial consultation is how we take the first look. In it, we examine the sentence for clear error while the 14-day window is still open, evaluate any cooperation posture against the Rule 35(b) timing rules, and tell you honestly whether this rule — or a different tool — fits your situation. If a Rule 35 issue may affect your sentence, book that hour now.