Exhibit 99.1 Vertex Announces First Quarter 2024 Financial Results KING OF PRUSSIA, PA – May 8, 2024: Vertex, Inc. (NASDAQ: VERX) (“Vertex” or the “Company”), a leading global provider of indirect tax solutions, today announced financial results for its first quarter ended March 31, 2024. “The year is off to a solid start, and I am very pleased with our financial performance in the first quarter,” stated David DeStefano, Vertex’s President, Chief Executive Officer and Chairperson of the Board. “Revenue trac ...