In 2019, we identified the highest proportion  of people having informal jobs (these are jobs without constitutional work rights, without formal job contract): 41.4% (Brazilian Institute of Geography and Statistics, n.d.). Data from a National Survey from 2015 (PNAD), showed that among the private sector, 20.6% of the workers were informal workers (that means without formal job contract) (Brazilian Institute of Geography and Statistics, 2015b).

References:

Brazilian Institute of Geography and Statistics. (n.d.). Desemprego cai para 11,8% com informalidade atingindo maior nível da série histórica. Retrieved December 3, 2019, from https://agenciadenoticias.ibge.gov.br/agencia-noticias/2012-agencia-de-noticias/noticias/25534-desemprego-cai-para-11-8-com-informalidade-atingindo-maior-nivel-da-serie-historica

Brazilian Institute of Geography and Statistics. (2015b). Pesquisa Nacional por Amostra de Domicílios—2015. https://biblioteca.ibge.gov.br/visualizacao/livros/liv98887.pdf