
From 1997 to 1999 he worked at the Privatization area of BNDES – Banco Nacional de Desenvolvimento Econômico e Social. He was a tax lawyer at Ernst & Young Auditores Independentes (De Rosa, Siqueira Advogados) from 1999 to 2001.
He was responsible for the tax area of Brasif (importation and retail sectors) – 2001 to 2006. Between 2006 and 2009, he was a tax consultant at Leoni Siqueira Advogados.
He is the founding partner of Guerra e Doin Advogados (since 2009).
Guilherme was also a professor of “Transfer Pricing” topic at a Foreign Trading course at Universidade Cândido Mendes. Author of several articles and co-author of the book “Environmental Tax Law.” (“Direito Tributário Ambiental”).
He earned a Bachelor of Law degree from Universidade Cândido Mendes and a Postgraduate degree in Tax Law at Fundação Getúlio Vargas (FGV-Rio).
Enrolled with OAB-RJ and OAB-SP.
Associated with Associação Brasileira de Direito Financeiro – ABDF and International Fiscal Association – IFA.