najohal, it's not an actual 'file' ... its one of those drop down menu options when requesting ATIP (Access to Information and Privacy) /GCMS (Global Case Management System) notes you can choose either one of these:
1) Privacy Act (Under this Act, only the sponsor's information can be obtained assuming the applicant (the sponsored person) is not in Canada on a visit visa or student visa or any other visa ... if you order notes under this Act, it's free which I find helpful because I usually wanna know whether they received additional documents which I send them AND any notes made by the officer. Both are available under this Act.
2) Information Act (Under this Act, you can get both your husband (principal applicant) and your (sponsor) information given he (your husband) has given you authorization to access his part of information. You can get that by filling out IMM5476 Authorize a Rep. and have him sign and you sign as well and them attach this signed form when requesting notes under this Act. This form can be downloaded from
http://www.cic.gc.ca/english/pdf/kits/forms/imm5476e.pdf
You will have to pay $5 fee (you may use your credit card)) You can get every piece of info. under this Act ... that's why maybe they charge you fee.
Does this help a bit?
