The next Census Survey won't take place until 2020. But, the Census Bureau recently sent out a letter to 1.2 million households asking them to fill out the 2015 National Contest Test.
The goal of the test is to improve questions and participation by testing out Internet options. If you received this letter, it's not a scam and you are required by law to fill it out. By responding, you are helping to improve the survey and test out some cost saving measures for the Census.