The U.S. Census Bureau conducts many different surveys and or censuses. So, it's possible you completed one of our others surveys like the decennial census.
The ACS collects data yearly about our education, housing, jobs and other characteristics, showing how we live and the economic and social needs of our communities.
If your household received the ACS, your response is important and required by law (Title 13, U.S. Code).
It's very unlikely you'll receive an ACS more than once every five years. However, individuals who move to a new address may receive the survey again in that five-year period.