[1] It elects one deputy to the lower house of Congress for each three-year legislative session by means of the first-past-the-post system.

Votes cast in the district also count towards the calculation of proportional representation ("plurinominal") deputies elected from the fifth region.

[2][3] Michoacán lost its 12th district in the National Electoral Institute's 2022 redistricting process.

[7][8] Under the 1996 districting plan, the district's head town was at Zamora de Hidalgo and it covered a different set of seven municipalities: Chavinda, Chilchota, Ixtlán, Jacona, Tangamandapio, Tangancícuaro and Zamora.

[9][8] The districting scheme in force from 1978 to 1996 was the result of the 1977 electoral reforms, which increased the number of single-member seats in the Chamber of Deputies from 196 to 300.