I am going to make a UK visa application for my wife who is currently working as an engineer in a firm for the last 6 months. She gets her salary by cash in hand and we usually keep it with us at home. She will be supporting herself for the visit as she will be travelling alone. Now although her bank account is active for more than 6 months but she has recently deposited all her savings in the bank. How can I prove the recent sudden increase in her bank balance. What evidence should I submit for the proof of this deposit other than her payslips and salary certificate.