Its really nice that your are having so much curious on this aspect, its good to know about every information regarding CA .Well here is the answer,
Following are some of the eligibility requirements for ICAEW(Institute of Chartered Accountants in England and Wales) members to become ICAI member:
1.ICAEW members should be current members of the ICAEW with no disciplinary findings.
2.ICAEW members should be qualified as ICAEW members being passed atleast the final examination of the ACA.
3.ICAEW members should undertake their training agreement or training contract within public practice.
4.ICAEW members should pass specified ICAI examinations.
Also note this:
• The members who have joined ICAEW through reciprocal arrangements with some other accountancy body are not eligible to join ICAI through ICAI/ICAEW MoU.
• ICAEW members who have completed their training agreement outside public practice are not eligible to join ICAI through ICAI/ICAEW MoU.