Continuous representation tolls the running of the statute of limitations, which commences when the attorney mistake is made.  Continuous representation exists because it is inequitable to require a client to sue its attorney while the case is still ongoing.  That said, there are many requirements as can be seen in Walsh v Wallace Law Off.  2022 NY Slip Op 02218 [203 AD3d 684] March 31, 2022 Appellate Division, First Department.

“Defendants established prima facie that this legal malpractice action was time-barred, as it was commenced on May 26, 2020, more than three years from the date it accrued. The three-year statute of limitations began to run on March 16, 2017, when a consent to change attorney form was executed by plaintiff, defendant Wallace Law Office, and defendant Leav & Steinberg, LLP (L&S), the incoming counsel (CPLR 214 [6]; Frost Line Refrig., Inc. v Gastwirth, Mirsky & Stein, LLP, 25 AD3d 532, 532-533 [2d Dept 2006]). The form was also notarized by a name partner of L&S. This unambiguous written document constitutes documentary evidence that the attorney-client relationship between plaintiff and the Wallace defendants ended more than three years before plaintiff commenced this action (see Seaman v Schulte Roth & Zabel LLP, 176 AD3d 538, 539 [1st Dept 2019]).

We reject plaintiff’s argument that Supreme Court erred in failing to consider the doctrine of continuous representation. The complaint alleged no “clear indicia of an ongoing, continuous, developing[,] and dependent relationship between the client and the attorney” or a “mutual understanding of the need for further representation on the specific subject matter underlying the malpractice claim” (Matter of Merker, 18 AD3d 332, 332-333 [1st Dept 2005] [internal quotation marks omitted]). Equally unavailing is plaintiff’s speculative contention that discovery is required as to the nature, if any, of the Wallace defendants’ continuing involvement in plaintiff’s underlying personal injury lawsuit.”