From the US government's ICE website here:
What are the guidelines for off-campus employment of F-1 students based on severe economic hardship?
USCIS makes case-by-case decisions for off-campus employment for students who can show that new, unexpected circumstances beyond their control have created severe economic hardship. These may include the following:
- Loss of financial aid or on-campus employment (if the student is not at fault)
- Large increases in tuition or living costs
- Substantial decrease in the relative value of currency the student depends upon to pay expenses
- Unexpected changes in the financial conditions for a student's sources of financial support
- Unexpectedly large medical bills not covered by insurance
- Other substantial, unexpected expenses
An F-1 student must have remained enrolled for at least one academic year, in status and in good academic standing before USCIS will authorize off-campus employment.
The F-1 student must be unable to get on-campus employment, or the pay from available on-campus employment must be insufficient to meet financial needs.
For each request approval, a DSO must provide the F-1 student with a Form I-20, "Certificate of Eligibility for Nonimmigrant Student Status," endorsed to that effect.
The F-1 student must file a Form I-765, "Application for Employment Authorization," and pay a fee to USCIS. The student should file within 30 days of the day the DSO endorses the Form I-20. If USCIS approves the application, the student will receive a Form I-766, "Employment Authorization Document," (EAD) from USCIS and can begin working.
Approval for off-campus employment is good for one year. If the F-1 student needs to continue working off-campus, the student must re-apply.