Filing a number of different forms with the United States Citizenship and Immigration Services can be a costly endeavor due to the fact that the great majority of them require a fee. Immigration form fees are the primary source of funding for USCIS, but you can request a waiver if you cannot afford to pay the fee.
If you are unable to afford the fees that are needed in order to file a number of immigration forms, then you can fill out the Request for Fee Waiver, the I-912. If you have filled out the form and know that you are eligible, you can then file it and have the rest of the supporting documentation also filled out (in English).
There are detailed instructions on the waiver that absolutely have to be followed, and once those steps have been completed you can then send the form to an office of the United States Citizenship and Immigration Services. You cannot send the fee waiver request via the internet.
Whether or not you are eligible for the fee waiver is dependent on your income as well as the number of people that live in your household. You are eligible if you live under the 150% poverty line, a line that takes into account your level of income in relation to your household size. You can also be eligible for the fee waiver if you have been enduring a period of financial difficulties due to unexpected circumstances, such as being hospitalized.