If your state’s human rights agency enforces laws that include more bases of discrimination in their statutes that affect your case, you may want to use the state agency. For example, many states are adding sexual orientation as a basis of discrimination to state laws, while it is still not included in the laws that the EEOC enforces.
If your state agency can process a discrimination complaint quicker than it takes for your local EEOC office, you may want to file with the state agency. If you are sure that you want to pursue the complaint in the state court system instead of the federal court system, you may want to file your complaint with the state agency. You can always elect to file with the state agency but also do a dual filing with the EEOC.
Remember that the time limits for the state’s human rights agency may differ from that of the EEOC. If you are only filing with the state agency, or are filing with both the state and the EEOC, you will need to adhere to the state deadlines.