A “supplemental” bill of particulars and an “amended” bill of particulars are two different things. The distinction is not without a difference, as it can affect whether a particularized claim may be presented at trial.

The well-worn purpose of any bill of particulars is to amplify the pleadings, limit the proof, and prevent surprise to an adversary at trial (L.R. v. Evergreen Charter School, 232 A.D.3d 920 [N.Y. App. Div., 2d Dep’t 2024]; Rich v. Donnenfeld, 191 A.D.3d 909 [N.Y. App. Div., 2d Dep’t 2021]). A “supplemental” bill of particulars, which is identified for personal injury actions in Rule 3043(b) of the New York Civil Practice Law and Rules (“CPLR”), permits a party to update continuing special damages and disabilities. A party may do so without leave of court at any time, but not less than 30 days before trial. The statute specifically directs that no new cause of action and no new injuries be raised in the supplemental bill (L.R. v. Evergreen Charter School, 232 A.D.3d at 922) underscoring its limited purpose as an “update” about previously-disclosed continuing damages and disabilities.

 That restriction makes sense, particularly when the supplemental bill is served after the filing of a note of issue after discovery has been completed. Upon seven days’ notice, according to the statute, another party may seek discovery with respect to the updated special damages and disabilities. The tight timeframe represented by the seven days recognizes that a post-note date of trial is approaching.

By contrast, an amended bill of particulars may add entirely-new grounds for liability and new injuries that were absent from the earlier bill. Its governing statute is Rule 3042(b) of the CPLR. A bill of particulars may be amended once as of right, and only prior to the filing of a note of issue (McEleney v. Riverview Assets, LLC, 201 A.D.3d 1159 [N.Y. App. Div., 3d Dep’t 2022]). Any further amended bill may only be served with leave of court. The absence of leave renders the amended bill a nullity (Campbell v. Dwyer, 185 A.D.3d 777 [N.Y. App. Div., 2d Dep’t 2020]). Where new theories or damages are alleged in an amended bill, further discovery may be undertaken if no certificate of readiness has yet been filed declaring discovery complete.

Supplemental and amended bills of particulars are not defined by how an attorney titles the documents. Regardless of title, the documents are viewed by courts based on their substantive contents. Therefore, issues such as the additional particulars’ timeliness, and their permissible number, will be resolved based on what the document actually “is” and not by what it is “called” by counsel. A somewhat recent example is seen in Naftaliyev v. GGP Staten Island Mall, LLC, 204 A.D.3d 932 (N.Y. App. Div., 2d Dep’t 2022), where the plaintiff served what was denominated as a post-note of issue supplemental bill of particulars, but which in reality added entirely new injuries that had not been previously asserted. The defendant moved to strike the “supplemental” bill, and on appeal, the Appellate Division held that it should have been stricken as it was, in fact, an “amended” bill for which leave of court had not been sought or obtained.

The distinction between supplemental and amended bills of particular is occasionally and impactfully seen when further particulars are provided by a party post-note of issue, which is permissible for the supplemental variety but impermissible for the amended variety (Jeannette S. v. Williot, 179 A.D.3d 1479, reargument denied by 185 A.D.3d 1480 [N.Y. App. Div., 4th Dep’t 2020]). By case law, a party may seek leave to serve an amended bill of particulars after the note of issue has been filed, but the motion will be denied if there has been an inordinate delay in making the motion measured from the date of the note of issue (Cesarz v. Reilly, 194 A.D.3d 1007 [N.Y. App. Div., 2d Dep’t 2021]) and the plaintiff has failed to establish both a reasonable excuse for the delay and the merit of the proposed amendment (Canals v. Lai, 132 A.D.3d 626 [N.Y. App. Div., 2d Dep’t 2015]). If leave to serve an amended bill is sought on the proverbial eve of trial, the court may grant it only sparingly (Green v. New York City Hous. Auth., 81 A.D.3d 890 [N.Y. App. Div., 2d Dep’t 2011]). Ultimately, leave is left to the discretion of the trial court, and appellate review will depend on whether such discretion is exercised providently.

If, pre-note of issue, counsel included in the bill of particulars or amended bill the information necessary to support all theories of liability, then the inability to do so after the filing of a note of issue should never be a problem for supplementing the bill(s) post-note of issue. Bills and amended bills should therefore be written in a manner that is thorough and complete.

Hon. Mark C. Dillon is a Justice of the Appellate Division, Second Department, an Adjunct Professor of New York Practice at Fordham Law School, and a contributing author of CPLR Practice Commentaries in McKinney’s.