He held various government positions during the Viceroyalty of Peru, serving as alcalde and regidor of Buenos Aires.

[5] For several periods he was chosen as Alférez real, in charge of carrying the Royal Standard during official ceremonies.

In 1702 by a Royal Provision issued in Barcelona on April 22 of that year, Alpoin was granted the title of Captain of the Caballería of the Fort of Buenos Aires.

[11] Juan Báez de Alpoim was the owner of the first Luxury Carriages of Buenos Aires, introduced in the city towards the end of the 17th century.

[13] His first wife was a descendant of Pedro Álvarez Holguín de Ulloa and Vasco Fernandes Coutinho, conquerors of Spanish and Portuguese origin.