KAP Gideon Adi & Rekan was established in 2012. Our people have a wide experience in handling various client such as mining, manufacturing, service, IT, etc. In 2016 KAP Gideon Adi & Rekan became a member of MGI Worldwide a leading global network of independent professional accounting and consulting firms. We are now known as MGI Gideon Adi & Rekan.
In Indonesia, MGI Worldwide is represented by MGI Gideon Adi & Rekan for consulting and assurance and non-assurance services. The firm has ten partners and about sixty senior and junior staff members The partners and professional staffs are members of the Indonesia Accountant Association and Indonesia Advocate Association. The firm provides auditing and assurance, tax, legal, information technology consultancy, and other related services such as corporate secretarial, financial and commercial advisory. Clientele of the firm ranges from individuals to multi-national corporation and listed companies engaged in various type of business.



Gideon Adi Siallagan

Gideon Adi Siallagan, received his Master and Bachelor of Science Degree in Accounting from University of Indonesia. Prior establishing KAP Gideon Adi & Rekan Gideon started his career with one of big four accounting firm in 1999. Gideon worked for Asian Development Bank, World Bank, and other NGOs. Gideon has served both public and privately held companies in a variety of industries, including manufacturing, mining, investment, government and nonprofit organizations. Gideon provide audit and assurance services, financial due dilligence services and business advisory service for a wide range of clients.



Bisner Sitanggang

Bisner Sitanggang received Bachelor of Accounting from Nommensen University, Medan . He got his Certified Public Accountant (CPA) in 2000. He has more than 20 years experience in accounting firm. His expertise are in auditing of mining sector, financial institution and in auditing of State owned enterprise. Out of auditing, she is also experience in corporate restructuring and merger acquisition process.



Valiant Great Ekasaputra

Valiant Great received Bachelor of Accounting from Airlangga University. He got his Certified Public Accountant (CPA) in 2016.
He is a Chartered Accountant (CA) from The Indonesian Institute of Accountants. He has more than 9 years experience in accounting firm.



William Suria Djaja Salim

William received Bachelor of Accounting from Atma Jaya University and Magister of Accounting from Trisakti University. He has more than 12 years experience in Finance, Accounting, Tax and Audit in real sector  and more than 8 years’ experience working in Big Four Accounting Firm. He is a Certified Tax Consultant C (BKP), Accountant Professional Education (Ak) from Trisakti University, Chartered Accountant (CA) and Certified Public Accountant (CPA).







Joyada Siallagan

Joy, received his Bachelor of Science degree in Taxation from University of Indonesia. Currently he is pursuing his doctoral degree in Bankruptcy Law. Joyada has solid experience in handling corporate tax planning as well as tax dispute. Joyada has appeared before the tax court handling tax disputes. Currently he is pursuing his doctoral degree in Bankruptcy Law. Joyada is a member of Indonesia Tax Lawyer, Advocate Association, and member of administrator bankruptcy.



Wilham George Louhenapessy

Mr Louhenapessy received his PhD in Geomechanics and Finite  Element Model from University of Wales Swansea (Swansea University), Wales, UK. He is a Senior Structure and Geotechnical Engineer.  He has more than 20 years of professional experiences on numerous national projects and a secondment task in Singapore, includes 5 years of research experience at  Swansea University, UK, where he and the team developed computer algorithms for Geotechnical/ Geomechanics software worldwide. He has been assisting Jakarta Municipality (Pemprov DKI Jakarta) on Monorail Project and Superelevated Highway in Mega Kuningan Jakarta; BATAN (The National Nuclear Energy Agency of Indonesia) on Bangka Island Nuclear Power Plant Siting Project in 2011-2012; Royal HaskoningDHV on various Mining Infrastructure, Open Pit and Mini Hydro Projects in Indonesia; Mott MacDonald on various infrastructure projects in Singapore and Indonesia; SNC  Lavalin on Detailed Engineering Design for two Power Plant (Talang Duku, South Sumatra and Krakatau Daya Listrik, Banten) and for PT MKSI on a tunnel Section of The CISUMDAWU Toll Road in West Java.



Musafran Harahap

Mr. Musafran holds master's degree and a bachelor’s degree majoring in accounting from the University of Sumatera Utara at Faculty of Economic and Business. He also is a Certified of Public Accountant-Indonesia and a member of the Indonesian Institute of Certified Public Accountants (IAPI).

Mr. Musafran has over 20 years of professional experience both in assignments in various industries, such as palm oil mill and palm plantations, manufacturing, harbor service and hospitality. He is also experience in assignments for state owned, NGO's and other industries