The main changes are described in the USCIS announcement regarding the new Form I-539.Basically, whereas before co-applicants who are applying for Extension of Status/Change of Status with the main applicant can be included on the same I-539, and each co-applicant would fill out an I-539 Supplement A (which was part of the same I-539 PDF), now each co-applicant would fill out the new Form I-539A.Furthermore, the main applicant and each co-applicant will now need to pay an $85 biometrics fee, whereas before for most types of Extension of Status/Change of Status, no biometrics fee was needed. So the cost for filing the new form is $370 + ($85 × number of applicants).