I am currently using ACS one-year surveys.
When I check the birth year of the infants (age<1) in a given ACS survey, their birth years are equal to the survey year for ALL infants. If I understand correctly, ACS survey is implemented every month throughout the year. Then, for example, if a household was surveyed in March of 2004 for 2004 ACS and if they have a 6-months-old infant, the birth year of this infant has to be 2003. But why do birth years of ALL infants same as the ACS year?