Mark O’Riordan

Mark joined Meridian in 1998 and was appointed Chairman and Chief Executive in October 2004. Prior to this he was Operations Manager at BBL Finance Ireland, an international merchant bank.

Since 1998, Mark has held a variety of executive positions within Meridian, namely Operations Director, Managing Director North America, Client Services Director EMEA and Director of Business Services, Mark also had responsibility for the Groups Treasury requirements during this time. Mark took over the position of Chairman and Chief Executive in 2004.

Mark is passionate about the business Meridian is involved in and personifies Meridian's commitment to delivering the highest quality services to its clients around the world. Mark is a qualified Chartered Accountant (FCA) and holds an MBA from The Open University.

Derek O'Brien

Derek was appointed Chief Operating Officer Tax Technology in 2018 with responsibility for leading the Tax Technology business and continues to have responsibility for Group Marketing in Meridian. Derek joined Meridian in March 2001 and has held several management positions during his time with Meridian and has been involved in New Product Development, Strategic Alliances and Go To Market.

In the more than 20 years with Meridian Derek has cultivated a strong and extremely productive relationships with a lot of our most strategic clients and partners. He began his career with some of Ireland’s largest retailers, in several operations management positions. Derek is a Graduate member of the Marketing Institute of Ireland (MMII Grad).

Michelle Lang

Michelle joined Meridian in 2013 and progressed to the role of Director of VAT Consulting in 2017. Michelle is responsible for leading the VAT consulting business in supporting and helping Meridian clients across a broad range of industries navigate intricate EU VAT laws. Michelle and her team provide expert VAT advice and practical guidance on all VAT issues, including, VAT issues arising from complex supply chains, VAT flow mapping, managing VAT compliance for businesses operating across multiple EU jurisdictions and handling audits with Tax Authorities. In addition to overseeing VAT consulting, since 2023, Michelle has led a team of consultants specialising in the implementation of Meridian's VAT determination products for SAP ; VAT Add-On and Arco.

Michelle has over 20 years of VAT experience, having worked at Deloitte before joining Meridian. Michelle holds a degree in Finance and is a qualified member of the Institute of Taxation in Ireland.

Niall O’Riordan

Niall joined Meridian as Head of Finance at the beginning of 2024. In this capacity he leads the finance team, overseeing financial strategy, operations and governance to drive business performance and ensure long term growth.

He began his career in BDO in 2014, where qualified as a Chartered Accountant. Following his qualification in 2019 Niall joined ION Group, a Technology Group with $3 Billion in revenue and over 10,000 FTE's, headquartered in Dublin. He held several key roles, including Revenue Accounting Manager and Head of Finance Processes and Governance. He played a key part in bond issuances, market reporting and finance transformation.