Part III: Pleadings, Motions, and Orders · Last amended November 1, 2016 · Last verified July 13, 2026
In one sentenceRule 15 spells out when a party may amend a pleading without permission, when it needs the court's leave, and when a late amendment still counts as filed on the original date.
(1)A party may amend its pleading once as a matter of course within:
(A)21 days after serving it; or
(B)if the pleading is one to which a responsive pleading is required, 21 days after service of a responsive pleading or 21 days after service of a motion under Rule 12(b), (e), or (f), whichever is earlier.
(2)In all other cases, a party may amend its pleading only with the court’s permission or the opposing party’s written consent. The party must attach its proposed amended pleading to the motion to permit an amended pleading. The court should freely give permission when justice requires.
(3)Any required response to an amended pleading must be filed within the time remaining to respond to the original pleading or within 14 days after service of the amended pleading, whichever is later.
(1)When an issue not raised in the pleadings is tried by the parties’ express or implied consent, it must be treated in all respects as if raised in the pleadings. A party may move — at any time, even after judgment — to amend the pleadings to conform them to the evidence and to raise an unpleaded issue. But failure to amend does not affect the result of the trial of that issue.
(2)If, at trial, a party objects that evidence is not within the issues raised in the pleadings, the court may permit the pleadings to be amended. The court should freely permit an amendment when doing so will aid in presenting the merits and the objecting party fails to satisfy the court that the evidence would prejudice that party’s action or defense on the merits. The court may grant a continuance to enable the objecting party to meet the evidence.
(c)Relation back of amendments. An amendment to a pleading relates back to the date of the original pleading when:
(1)the law that provides the applicable statute of limitations allows relation back;
(2)the amendment asserts a claim or defense that arose out of the conduct, transaction, or occurrence set out — or attempted to be set out — in the original pleading; or
(3)the amendment adds a party, substitutes a party, or changes the name of the party against whom a claim is asserted, if paragraph (c)(2) is satisfied and if, within the period provided by Rule 4(b) for serving the summons and complaint, the party to be brought in by amendment:
(A)received such notice of the action that it will not be prejudiced in defending on the merits; and
(B)knew or should have known that the action would have been brought against it, but for a mistake concerning the proper party’s identity.
(d)Supplemental pleadings. On motion and reasonable notice, the court may, on just terms, permit a party to file a supplemental pleading setting out any transaction, occurrence, or event that happened after the date of the pleading to be supplemented. The court may permit supplementation even though the original pleading is defective in stating a claim or defense. The court may order that the opposing party respond to the supplemental pleading within a specified time.
Amendment History
Amended effective May 1, 2014; November 1, 2016.
Advisory Committee Notes
Advisory Committee Notes
Although the precise language is different for purposes of clarity, the 2016 amendments to Utah Rule of Civil Procedure 15(c) adopt the approach of Federal Rule 15(c) regarding the relation-back of an amended pleading when the amended pleading adds a new party.
Plain-English Summary
Rule 15 governs changes to a pleading after it's filed. A party can amend once as a matter of course — without asking anyone — within 21 days of serving the original pleading, or, if a response is required, within 21 days after that response is served or 21 days after a Rule 12(b), (e), or (f) motion is served, whichever comes first. After that window, a party needs either the court's permission or the opposing party's written consent, and the court is directed to give that permission freely when justice calls for it. A party seeking permission must attach the proposed amended pleading to the motion. Once a pleading is amended, any required response is due within whatever time remained to respond to the original pleading, or 14 days after the amendment is served, whichever is later.
Rule 15 also addresses amendments that surface during or after trial. If the parties try an issue that wasn't in the pleadings, without objection, the court treats it as if it had been pleaded all along, and a party can move to amend at any time, even after judgment, to match the pleadings to the evidence. If a party does object that evidence falls outside the pleadings, the court can still allow an amendment, and should do so freely when it will help resolve the case on the merits and the objecting side can't show it would be prejudiced; the court can grant a continuance to let that side respond to the new evidence.
The relation-back doctrine in Rule 15(c) lets an amendment count as if it were filed on the date of the original pleading — a critical protection when a statute of limitations has run in the meantime. Relation back applies when the applicable statute of limitations itself allows it, when the amendment arises from the same conduct, transaction, or occurrence already described in the original pleading, or when the amendment corrects the identity of a party, provided the new party learned of the action in time to avoid prejudice and knew or should have known it would have been named but for a mistake about identity. Finally, Rule 15(d) lets a party file a supplemental pleading, with the court's permission, to add events that happened after the original pleading was filed — even if that original pleading had its own defects.
Frequently Asked Questions
Can I amend my complaint without asking the court?
Yes, within limits. Rule 15(a)(1) lets you amend once as a matter of course within 21 days of serving the original pleading, or, if a responsive pleading is required, within 21 days after that response is served or 21 days after a Rule 12(b), (e), or (f) motion is served, whichever is earlier. Outside that window, you need the court's permission or the other side's written consent.
What does it mean for an amendment to 'relate back'?
It means the law treats the amended pleading as though it were filed on the date of the original pleading, rather than the later date it was filed. That matters most when a statute of limitations has expired between the two filings. Relation back applies when the amendment arises from the same conduct, transaction, or occurrence already in the original pleading, among other conditions in Rule 15(c).
Can I fix a defendant's name after the statute of limitations has run?
Sometimes. Rule 15(c)(3) allows an amendment that corrects a party's identity to relate back to the original filing date if the underlying claim already satisfies Rule 15(c)(2), and if, within the time Rule 4(b) allows for serving the summons and complaint, the new party got enough notice of the action to avoid being prejudiced in defending it, and knew or should have known it would have been sued but for a mistake about its identity.
Can I amend my pleadings in the middle of trial?
Yes. If an issue outside the pleadings gets tried by the parties' consent, express or implied, Rule 15(b)(1) treats it as if it had been pleaded, and either side can move to amend — even after judgment — to match the pleadings to what was tried. If a party objects that evidence falls outside the pleadings, the court can still allow an amendment under Rule 15(b)(2), and should do so freely when it would help resolve the case .
What's the difference between an amended pleading and a supplemental pleading?
An amended pleading revises what's already alleged, usually about events that happened before the original pleading was filed. A supplemental pleading, allowed under Rule 15(d) on motion and notice, adds new transactions, occurrences, or events that happened after the pleading being supplemented was filed. The court can permit a supplemental pleading even if the original pleading had its own problems.
Source & verification. Rule text, Advisory Committee Notes, and
amendment history are reproduced verbatim from the Utah Rules of Civil Procedure,
adopted by the Utah Supreme Court. Last verified July 13, 2026. ·
Official source
Also known as:amend complaint utahamended pleading utahrelation back amendment utahleave to amend utahsupplemental pleading utahutah rule 15amend pleading as a matter of course