I just moved to Illinois 4 weeks ago, can I file Bankruptcy here or do I have to go back to where I lived last month?
The residency requirement for filing bankruptcy is that you have to have lived in the area where you are filing for the better part of 180 days. That is, you must have lived in the area where you will be filing for more days than in any other area. If you are desperate to file (trying to stop a foreclosure) you will need to return to where you came from. Otherwise, you can wait until you've lived here for 91+ days.
Notwithstanding the residency requirement, the exemptions you will be allowed to be applied to your property will be calculated according to the state exemptions where you have resided for the better part of the past two years. What this means is, if you lived in California for 89 of the last 180 days and then live in Illinois for 91 of the past 180 days you can file for bankruptcy in Illinois, but will be required to use California exemptions for the processing of your case.
