Constitutional quota details

https://www.constituteproject.org/constitution/Burundi_2018?lang=en 2018 constituion 

The National Assembly is composed of at least 100 deputies in rates of 60% Hutu and 40% Tutsi, of which a minimum of 30% must be women, elected by direct universal suffrage for a term of 5 years and 3 deputies issuing from the Twa ethnicity co-opted according to the electoral code. 

In the case that the results of an election do not reflect the percentages outlined above, it proceeds to the rectification of corresponding imbalances by means of cooptation provided for in the Electoral Code. (Article 169)