Hi everyone,
i am using IPUMS USA Data from 2006-2016 to analyse how the 2008 financial crisis impacted economic outcomes like employment and income. I came across issues during my analysis that relate to the lack of data (?) on when the survey was conducted exactly.
1)Variables related to income refer to the 12 months before the survey was conducted. How can i deal with this rolling time period when trying to analyse the impact of the financial crisis on income. Furthermore, the value of this variable does not always correspond to the survey year (i.e. if the survey was completed in Jan 2008, the income represents the yearly income for 2007).
2)Employment Status is given for a certain point in time. However, i do not know whether this individual was fully impacted by the financial crisis (Jan 2008 vs Dec 2008).
Any ideas or recommendations on how to deal with this timing issue is greatly appreciated 
As you state, the ACS data are collected on a rolling basis over the course of the year. The public use data does not contain any data or variables that contain information on interview date or time. Documentation from the Census explains how to interpret annual and five-year period estimates. It clarifies that the ACS estimates do not represent a specific point in time during the collection period, but rather a pooling of the data collected during the entire period. For 1-year estimates, the ACS uses data collected in that calendar year — January 1 through December 31. When using the ACS, users should consider the extent of change in their topic of interest over the period when interpreting the period estimates.
To answer your specific questions, depending on your broader research questions and goals, you may consider using a data source with more precise data collection dates, such as the Current Population Survey. CPS data is collected and reported monthly and contains information on employment status, income and other relevant variables.