Beginning in January 2013, the ACS added an Internet self-administered data collection instrument as a new mode. This option was only available to mailable addresses in the United States. The ACS discontinued sending questionnaires in the initial mailing and instead sent households an invitation to fill out the survey on-line. Non-respondents received a questionnaire in the second mailing.

Starting October 1, 2012, the ACS reduced the Failed Edit Follow Up (FEFU) operation workload as a program cost-saving measure. Prior to that date, incomplete mail forms with missing content or missing population data were sent to FEFU. Starting October 1, 2012, the ACS only sent cases to FEFU for missing coverage; however, if there was missing content in those coverage cases, we collected the missing data. For more information, view the report Evaluation of the Effect on Item Nonresponse of Changes to the Failed Edit Follow-up Operation.

Because of the Federal Government shutdown in October 2013, the ACS did not collect data for the October panel. As result, the 2013 sample was smaller than the 2012 sample.