I am looking at the distribution of negative values in the ACS variable ftotinc between 2001 and 2012. I understand that this is a sum of multiple income sources across family members and negative values are generated by net losses. I have looked at the corresponding questionnaires. However, I am noticing that there is significant clumping around -9999 and I wonder if this is a result of bottom coding somewhere? Based on the documentation that I have read, there was no bottom coding after 2000. Can I assume that these are reported values?